Infrared and X-ray variability of the transient Anomalous X-ray Pulsar XTE J1810-197

合集下载

xrd衍射及应用

X射线衍射的方法及应用从1912年，马克思·冯·劳埃发现晶格中晶面的距离与X射线相近，晶体材料可以作为X射线天然的三维光栅以来。

X射线衍射逐渐发展成为了一种有效的高科技无损检测技术来分析许许多多的材料，包括流体、矿物、聚合物、药物、薄膜材料、陶瓷、半导体等等。

X射线衍射可以提供直观的材料的结构信息，如相、织构和平均晶粒尺寸、缺陷、结晶度等结构参数。

X-Ray Diffraction: Instrumentation and Applications（ANDREI A. BUNACIU; ELENA GABRIELA UDRI¸STIOIU; HASSAN Y. ABOUL-ENEIN. Critical Reviews in Analytical Chemistry.2015,45,289-299）这篇文章首先简单介绍了关于X射线衍射的基础理论，之后着重介绍了X射线衍射仪的原理构造、样品制备以及XRD技术在制药生产、法医学、地质学、微电子工业、玻璃制造以及腐蚀分析六个领域的应用。

Micro-XRD study of beta–titanium wires and infrared soldered joints（Masahiro Iijimaa,∗, William A. Brantleyb, Naoki Babac, Satish B. Alapatid,Toshihiro Yuasaa, Hiroki Ohnoe, Itaru Mizoguchia。

Dental Materials.2007,23，1051–1056）针对红外焊接的beta-Ti丝接头做了微区X射线衍射分析。

X-Ray Diffraction: Instrumentation and Applications（ANDREI A. BUNACIU; ELENA GABRIELA UDRI¸STIOIU; HASSAN Y. ABOUL-ENEIN. Critical Reviews in Analytical Chemistry.2015,45,289-299）中基础理论部分包括布拉格方程、X射线的发生以及测角仪的原理和光学布置等等，文章大致阐述了一下XRD的原理，这些与我们在课本上学到的基本一致。

x-ray操作中文手册_060911_V1.1

2d sinϑ = n λ
(2)
（d = 晶格间距； n = 衍射级）
假设 d 已知 X-射线的能量可通过掠射角ϑ 求出，ϑ 可
从光谱中获得，其关系如下：
E = h ⋅ f = hc / λ
(3)
结合公式（3）和公式（2），我们可知：
E = (n ⋅ h ⋅ c) /(2 ⋅ d ⋅ sinϑ)
(4)
同的能量。
设备的搭建和步骤如图 Fig.1 所示搭建实验设备。在 X-射线的射出管端固定光阑管 (1mm 直径的管子使用 LiF 晶体,2mm 直径的管子使用 KBr 晶体)。关闭 X-射线装置,将计数器和角度计连接到实验设备中的基区板上合适的插座中去。调整角度计，同晶体分析仪一起放在中间,设置计数管右侧止动。
KBr analyzer(Fig.5)
n=1
13.5 Kα 8.059
12.3 K β 8.831
n=2
28.0 Kα 8.015
25.1 K β 8.870
n=3
44.6 Kα 8.038
39.3 K β 8.911
n=4
69.4 Kα 8.039
57.6 K β 8.893
Fig. 5: 铜的 X-射线的强度作为掠射角的函数；
Monochromatization of copper X-rays
25
7 钼 X-射线的 Kα 线的二重分裂/精细结构
Kα doublet splitting of molybdenum X-rays /fine
structure
29
8 铁 X-射线的 Kα 线的二重分裂/精细结
Kα doublet spilitting of iron X-rays / fine structure 33

10.1007@s10562-014-1436-9

Polymer-Encapsulated Metallic Nanoparticles as a Bridge Between Homogeneous and Heterogeneous CatalysisElad Gross •F.Dean Toste •Gabor A.SomorjaiReceived:6October 2014/Accepted:13November 2014ÓSpringer Science+Business Media New York 2014Abstract Continuous efforts in catalysis research have been devoted towards the development of heterogeneous catalysts that can activate reactions which are catalyzed by homogeneous catalysts.Replacing homogeneous catalysts with their heterogeneous counterparts will enhance the sustainability of the catalytic system,providing a highly recyclable,scalable and efﬁcient setup.Throughout this review we demonstrate that small (\2nm),metallic na-noclusters can catalyze a wide range of p -bond activation reactions that were previously activated by homogeneous catalysts.The small size of the nanoparticles enables their reversible oxidation into catalytically active metal ions.Encapsulation of the metal within a polymeric matrix severely restricts leaching of the highly oxidized metal ions into the solution phase,inducing high catalytic sta-bility and recyclability.Activation of complex,multistep organic transformations with heterogeneous catalysts provides novel opportunities,not accessible with homo-geneous catalysts,to control and tune the products selec-tivity.By designing the molecular properties of the polymeric matrix that encapsulates the metal cluster,high products selectivity,diastereoselectivity and enantiose-lectivity can be gained.These results demonstrate the capability of mesoscale catalysts,constructed of metallic nanoparticles and an encapsulating layer,to activate a wide array of catalytic reactions with high reactivity and tunable selectivity.Keywords Heterogeneous catalysis ÁHomogeneous catalysis ÁAsymmetric catalysis ÁCyclization ÁInfrared tomography ÁNEXAFS ÁColloidal synthesis1IntroductionCatalysis is a critical science for the modern society and improvements in catalytic processes will increase efﬁ-ciencies of chemical transformations while reducing waste and environmental footprints.Highly selective catalysts,especially those that can be readily recycled,are vital for the development of sustainable chemical processes that can address the energy-related challenges of the 21st century [1–3].Therefore,the development of modular catalytic systems,in which different parameters within the catalyst can be tuned for optimization of its catalytic properties and reaction scope,are highly desirable.The variability of homogeneous catalysts,constructed of a metal-ion core and surrounding ancillary ligands,enables the tuning of the catalyst’s structure for optimization of its reactivity and selectivity [4,5].For example,in homoge-nous catalysts,the steric and electronic features of the ancillary ligands are commonly varied in order to attain high stereoselectivity.In addition to the ligands,the ionic properties of the metal play a fundamental role during the catalytic process,since the catalytic reactivity is governed by metal-reactant interactions that are related to the oxi-dation state of the metal [6].E.Gross (&)ÁF.Dean Toste ÁG.A.Somorjai Department of Chemistry,University of California,Berkeley 94720,CA,USAe-mail:elad.gross@mail.huji.ac.ilE.Gross ÁF.Dean Toste ÁG.A.SomorjaiChemical and Materials Science Divisions,Lawrence Berkeley National Laboratory,Berkeley 94720,CA,USAPresent Address:E.GrossInstitute of Chemistry,The Hebrew University of Jerusalem,Jerusalem,IsraelCatal LettDOI 10.1007/s10562-014-1436-9Heterogeneous catalysts,on the other hand,lack the high tunability of homogeneous catalysts but have the advantages of being readily recyclable and easily adopted in aﬁxed-bedﬂow reactor.The robustness,stability and recyclability of heterogeneous catalysts under harsh con-ditions makes them ideal catalysts for cleavage of strong bonds,such as C–O and C–H bonds.However,heteroge-neous catalysts lack the high products selectivity(e.g. diastereoselectivity,enantioselectivity)which is routinely obtained while employing architecturally-designed orga-nometallic complexes as homogeneous catalysts.The cat-alytic reactivity of heterogeneous catalysts can be moderately optimized by adjusting the nanoparticle’s size, shape and the support on which it is deposited[7–10].The limited reaction scope of heterogeneous catalysts empha-sizes the lack of novel catalytic systems that can combine the recyclability of heterogeneous catalysts along with the wide reaction scope and high selectivity of homogeneous catalysts[11].Continuous efforts have been devoted to activate het-erogeneous catalysts toward reactions that are mainly performed with homogeneous catalysts[12].The conven-tional method of heterogenizing homogeneous catalysts relies on grafting highly selective transition metal complex catalysts onto mesoporous solid supports.It has been demonstrated that the supported metal sites can catalyze a variety of reactions,such as oleﬁn methathesis and Zie-gler–Natta depolymerization,with high reactivity and recyclability[13].Another alternative for heterogenizing homogeneous catalysts is to directly embed homogenous catalysts within the structure of metal-organic frameworks.Highly selective solid catalysts were prepared by encapsulating catalytically-active sites within well-deﬁned frameworks,which have speciﬁc pore dimensions and topologies[14–17].For example,it was recently demonstrated that asymmetric hetero-Diels–Alder reactions can be activated by embed-ding catalytically active Ti(IV)ions within NbO-type chiral metal-organic frameworks[18].A more challenging approach is to utilize the truly heterogeneous metallic nanoparticles as catalysts for reactions that are activated by homogeneous catalysts.In the recent years a variety of metallic nanoparticles,such as Au[19–29],Pt[30,31],and Pd[32]have been employed as catalysts for complex organic transformations with high yield and selectivity. Spectroscopic measurements have indicated that the heter-ogeneous catalysts have to be partially charged prior to their activation as catalysts toward organic transformations.Two main approaches were taken in order to change the elec-tronic properties of heterogeneous catalysts:(i)In theﬁrst approach the metallic nanoparticles arecharged following their deposition on an acidic orbasic metal-oxide support[33,34].For example,itwas demonstrated that the deposition of Au nano-particles on CeO2support facilitates the oxidationof the metallic(Au0)nanoparticles into Au?3.X-ray spectroscopy measurements correlatedbetween the oxidation state of the metal and itsreactivity toward coupling reactions that werepreviously activated by Au ions[29–32].(ii)In the second approach,the oxidation state of the nanoparticles and as a consequence also theircatalytic reactivity,are tuned by controlling thesize of the nanoparticles.It was previously dem-onstrated that there is a direct correlation betweenthe nanoparticle’s size and its electronic properties[35,36].The oxidation state of nanoparticles canbe transformed from metallic into ionic by decreas-ing the nanoparticles size below2nm.The forma-tion of small,highly oxidized nanoparticles withionic properties change the catalytic properties ofthe metal and activate the clusters toward a varietyof reactions which were previously catalyzed byhomogeneous catalysts[37].The partial oxidation of the metallic nanoparticle transforms the properties of the heterogeneous catalyst, making it similar to the metal ion core of homogeneous catalysts.However,the high selectivity of homogeneous catalysts is mainly gained by the ligands which surround the metallic core.These directing ligands are not present within heterogeneous catalysts.As a consequence,only in few cases heterogeneous catalysts showed similar products selectivity to that obtained by their homogeneous ana-logues[38].In the following review paper we describe our recent work in heterogenizing homogeneous catalysts.We dem-onstrate that by tuning the properties of metallic nanopar-ticles and embedding the nanoparticles in a speciﬁcally-designed polymeric matrix,the heterogeneous catalyst can be activated to promote a variety of organic transforma-tions.The polymeric matrix that encapsulates the metallic nanoparticle has two main roles:(i)The matrix stabilizes the small,highly oxidized,metallic nanoparticles and severely restricts theirdecomposition and leaching into the solution phase. (ii)The encapsulating polymer also acts as a co-catalyst and its properties can be tuned in order todirect the reactivity and selectivity of the metalcore.In order to analyze the impact of the nanoparticle’s oxidation state and its surrounding environment on the catalytic reactivity,a variety of in situ spectroscopy mea-surements have been conducted under reaction conditionsE.Gross et al.[39–42].Synchrotron based X-ray spectroscopy measure-ments have been performed in order to correlate between the oxidation state of the catalyst and its reactivity.In addition,synchrotron based FTIR microspectroscopy measurements tracked the reactants-into-products trans-formation and detected the role of different intermediates in the catalytic process.2Results2.1Dendrimer-Templated Synthesis of Small(*1nm)Metallic NanoparticlesMetal nanoparticles in the size range of 10nm and above have been widely synthesized by colloid techniques [7–10].However,the synthesis of nanoparticles with size below 1nm (tens of atoms)is more challenging.At this size regime,more than 90%of the atoms are located on the surface of the clusters.The atoms coordination number in these clusters is smaller than that of larger nanoparticles that have a substantial fraction of their atoms in the bulk.At sizes smaller than 1nm,the nanoparticles have shorter metal–metal bonds,lower melting points,and are easier to oxidize than larger particles.These properties also impact the catalytic reactivity of the nanoparticles [42].A dendrimer templating strategy is very attractive for synthesis of small nanoparticles [43–45].The size of metal nanoparticles synthesized within polyamidoamine (PA-MAM)dendrimers is controlled by the number of functional groups in the dendrimer and the structure of the dendrimer matrix (Fig.1).The number of internal tertiary amine groups dictates the maximum number of metal ions that can be encapsulated within the matrix and,therefore controls the nanoparticle’s size [46].The quasispherical hyperbranchedstructure of the dendrimer supplies internal cavities for nanoparticle’s growth upon reduction of metal ions.The dendrimer also provides a shell that prevents aggregation of the as-grown nanoparticles.By changing the metal ion to dendrimer concentrations ratio,a variety of monometallic and bimetallic nanoparticles in the size range of 1nm were synthesized with narrow size distribution [43–45].1nm sized dendrimer-encapsulated Rh and Pt nano-particles were synthesized and characterized with X-ray Photoelectron spectroscopy (XPS).Analysis of the spectra indicated that 44%of the Rh within the Rh nanoparticles was oxidized,whereas 93%of the Pt was oxidized in the Pt nanoparticles (Fig.2).These results demonstrate the direct correlation between the small size of the nanoparticle and their oxidation state.Dendrimer-encapsulated nanoparticles were immobi-lized within high surface-area mesoporous silica.Electro-static interactions and hydrogen bonding between the dendrimer’s matrix and the silica support anchored the encapsulated nanoparticles to the support,minimizing any leaching or aggregation of the nanoparticle.The dendri-mer-encapsulated nanoparticles were active as catalysts for ethylene hydrogenation reaction without any pretreatment [37].The catalytic reactivity indicates that even with the encapsulated matrix,most of the nanoparticle’s surface area is still accessible for activation of reactant molecules.After a mild reduction process at 423K in 76torr of H 2,the catalytic reactivity for ethylene hydrogenation was maximized due to reduction of the oxidized Rh and Pt nanoparticles.Preservation of the small particle size and its’catalytic reactivity after the pretreatments demonstrates the high stability of the encapsulated metal.However,pretreatment at higher temperature (673K)led to sintering of the nanoparticles,followed by a decrease in their cata-lyticreactivity.Fig.1Preparation scheme and HR-TEM image of dendrimer-encapsulated metallic nanoclustersPolymer-Encapsulated Metallic Nanoparticles2.2Dendrimer-Encapsulated Metallic Nanoparticlesas Catalysts for p -Activation Reactions 2.2.1Catalytic Properties of the Heterogeneous Catalyst As suggested by their oxidation state,dendrimer-encapsu-lated metallic nanoparticles have signiﬁcant electrophilic character that is similar to that of electron-deﬁcient,late-metal homogeneous catalysts.Following this observation,it was hypothesized that these catalysts would activate new solution-phase carbon–carbon and carbon–heteroatom reactivity that could not have been previously observed with heterogeneous catalysts.Dendrimer-encapsulated Pt nanoparticles were synthe-sized,loaded on mesoporous silica and their catalytic reactivity was tested toward a variety of organic transfor-mations [31].In order to further oxidize and activate the Pt nanoparticles prior to the catalytic reaction,the metallic clusters were exposed to PhICl 2;a reagent that acts as a mild oxidizer.Following this pretreatment,the heteroge-neous catalysts showed high reactivity towards hydroalk-oxylation reactions with yields generally [99%,which is similar to the reactivity of a homogeneous organometallic Pt complex (Fig.3).The reaction was performed at 100°C with toluene as an organic solvent.The silica-supported dendrimer-encapsulated Pt nanoparticle showed excellent recyclability over multiple cycles after simple ﬁltration,reduction and pretreatment with PhICl 2.A sample of silica loaded dendrimer-encapsulated Pt nanoparticle has been recycled four times with a consistent yield of [90%under the reported reaction conditions.Following its high reac-tivity in hydroalkoxylation reaction,the catalyst was tested toward additional p -bond activation reactions.The highly oxidized nanoparticles catalyzed several cyclization reac-tions in the solution phase under relatively mild conditions with minimal or no side reactions.The catalytic reactivity toward the hydroalkoxylation reaction was further enhanced when the Pt cluster in thedendrimer matrix was replaced with Pd cluster [32].High reactivity (95%yield)was obtained with reaction time of 4h at room temperature with dendrimer-encapsulated Pd nanoparticles,while only 5%yield was measured with the homogeneous catalyst (e.g.PdBr 2)under similar conditions.2.2.2Catalytic Reactivity Under Continuous FlowConditions Since no leaching of catalytically active species was detected from the dendrimer-encapsulated Pd catalyst during the batch-mode reaction,the catalyst was applied in a ﬁxed bed plug ﬂow reactor to catalyze the same reaction in a continuous-ﬂow mode [32].The transition from batch to ﬂow mode circumvents the necessity of separating the catalyst from the reaction medium [47].Furthermore,as long as the highly active heterogeneous catalyst can achieve a full conversion of reactants to products,any further puriﬁcation of the product is avoided.As shown by the blue dots in Fig.4a,dendrimer encapsulated Pd nano-particles,which were pretreated with PhICl 2,completed the reactant into product conversion at roomtemperature.Fig.2XPS spectra ofdendrimer encapsulated a Rh and b Pt nanoparticles.For Rh nanoparticles,44%of the Rh was oxidized,whereas 93%of the Pt was oxidized for the PtnanoparticlesFig.3Hydroalkoxylation of 1with Pt catalysts.To obtain electro-philic activity from the Pt NPs,pretreatment with the mild oxidant PhICl 2is required.Yields were determined by NMR versus internal standardE.Gross et al.However,the catalytic activity quickly deteriorated to less than 5%conversion after 15h.However,when the reac-tion solution contained 5mM of PhICl 2,the reactivity was restored and 100%conversion was observed for more than 10h.The dependence of product yield on reaction time indicates that the catalyst is deactivated faster if no oxi-dizing agent is present in the solution.When the oxidizing agent is introduced to the catalyst along with the reactant,the deactivated catalysts can be in situ reactivated.The continuous ﬂow mode reaction is a convenient tool for probing different kinetic parameters,such as the acti-vation energy of the catalytic reactions (Fig.4b).The reactivity at different reaction temperatures was measured in the ﬂow reactor and from which the apparent activation energy was determined to be 20.0kcal/mol.In order to measure the activation energy in a batch mode reaction,multiple reactions must be repeated at different tempera-tures.As a result,any operational error in these reactions will generate inaccuracy in the activation ing a ﬂow reactor,all reaction parameters can be controlled precisely and reproduced easily,while the only variable is the reaction temperature.It should be noted,however,that in order to extract kinetic data of catalytic reactions which are performed in ﬂow reactor,the reactivity should be constant throughout the measurements without any deac-tivation.In the example that is shown above,the activation energy was analyzed based on the reactivity during the initial 10h of the reaction in which no deactivation of the catalyst was detected.2.2.3Stability of the Heterogeneous CatalystAlthough the remarkable recyclability of the dendrimer-encapsulated nanoparticle is a strong indication for its heterogeneity,further veriﬁcation of the heterogeneous catalysts stability were performed [31].A three-phase testwas conducted with a resin-bound substrate [48,49].In the presence of the homogeneous catalyst,PtCl 2,26%con-version of resin-bounds substrate into product was observed.However,the oxidized dendrimer-encapsulated Pt nanoparticle resulted in less than 2%conversion (Fig.5a).In addition,transmission electron microscopy images of supported Pt clusters before and after the cata-lytic reaction did not show any appreciable aggregation or leaching (Fig.5b).Furthermore,an experiment was conducted in which the Pt clusters were embedded within a mesoporous silica pellet,to allow for facile removal of the reaction solution from the NP catalyst under reaction conditions (Fig.5c)[50].In this case,a solution of starting material,PhICl 2and solvent were added to the catalyst pellet in reactor A and began to generate the product.After 42%yield was achieved,the reaction solution in A was transferred to a new vessel with no catalyst B .The oxidized catalyst pellet remained in A .Following this step a fresh solution of starting material and solvent was added into A .The solu-tion in A began to convert to product while the solution in B did not react and remained at 42%yield.These results indicate that the active catalyst is truly heterogeneous.If any homogeneous species were present in the solution,it would have been transferred into vessel B and an increase in products yield should have been observed.Moreover,the new solution added to A started to react,showing that the active catalyst has,in fact,remained in A .2.3X-ray Absorption Spectroscopy and ReactionKinetic Studies of Dendrimer Encapsulated Metallic Nanoparticles In order to gain a mechanistic insight of the properties of dendrimer-encapsulated metallic nanoparticles X-ray absorption spectroscopy (XAS),including extendedX-rayFig.4a Time on stream of product yield catalyzed by dendrimer encapsulated Pd nanoparticles.In the presence of 5mM PhICl 2in the reaction stream the catalyst was more stable and was deactivated relatively slowly (red diamonds ),compared to the case when only reactant was ﬂowed through the reactor (blue dots ).b Activation energy determination of the hydroalkoxylation reaction catalyzed by dendrimer encapsulated Pd nanoparticles using a continuous ﬂow reactorPolymer-Encapsulated Metallic Nanoparticlesabsorption ﬁne structure spectroscopy (EXAFS)and near-edge X-ray absorption ﬁne structure spectroscopy (NEXAFS),were conducted [30].These measurements provide structural and composition analysis of the catalysts under solution-phase reaction conditions.To analyze composition–reactivity correlations of the Pt catalyst,samples with varying degree of oxidation were prepared by a sequence of pretreatments such as reduction by H 2and oxidation by PhICl 2.XAS studies showed that the coordination numbers and the oxidation state of Pt in the dendrimer-encapsulated metal clusters can be easily altered by cycles of reduction and oxidation treatment (Fig.6a).This effect was correlated to the small size (1nm)of the metal clusters.After an initial reduction pretreatment,the Pt–Pt coordi-nation number,derived from EXAFS analysis,was about 5,indicating an average particle size of about 1nm.Fol-lowing a subsequent oxidation treatment with PhICl 2,the Pt–Pt coordination number decreased to about one while the Pt–Cl coordination number increased to about 2.The second reduction treatment brought the Pt–Pt coordination number back to about 4.5,and the metallic cluster-structure was largely recovered.The changes in oxidation state of the catalyst were also reﬂected in the fractions of Pt(0),Pt(II),and Pt(IV)species obtained from NEXAFS analysis (Fig.6b).These results demonstratethatFig.5a A three-phase test to determine the presence of a homogeneous catalyst byleaching or release and capture.b TEM images of dendrimer encapsulated Pt nanoparticles,loaded on mesoporous silica before reaction (left ),and after treatment with PhICl 2and reaction with 1(right ).c A reaction vessel (A )was charged with a substrate,a pellet of catalyst and PhICl 2oxidant (blue section).The mixture was stirred and the yield was monitored (i ).When the reaction in vessel A reached 42%yield,the solution was removed and placed into a new vessel (B ).A fresh solution of starting material was added to vessel A where the catalyst pellet remained (yellow section).Both vessel A and B were then stirred and monitored (ii )E.Gross et al.the changes in both coordination numbers and oxidation state of Pt catalyst are reversible during the sequence of reduction and oxidation treatment.The evolution of the Pt chloride species in the catalyst was monitored by in situ NEXAFS under reaction condi-tions,in order to correlate the catalyst deactivation process with changes in the fraction of Pt active species (Fig.7).The reaction kinetics results showed that the conversion rate increased with the fractions of Pt(IV)species in the oxidized catalyst.Therefore,it was concluded that the Pt(IV)species was more active than the Pt(II)species.The evolution of the different fractions of Pt species by in situ XAS measurements revealed that the Pt(IV)species was not stable under reaction conditions,and was partially converted to the Pt(II)species as the reaction proceeds.The depletion of the fraction of the Pt(IV)species correlates with the catalyst deactivation which was observed in the reaction kinetics study.The aforementioned reversibility in the cluster’s struc-ture suggests that after oxidation Pt ions [both Pt(II)and Pt(IV)]can be stabilized inside the dendrimer without leaching.The increased stability was correlated to the differences between the hydrophobic solvent (e.g.toluene)and the hydrophilic components of the catalyst including the Pt ion,the PAMAM G4-OH dendrimer,and the silica support.These polar materials have a low solubility in toluene.Thus,as long as this catalyst is used in a nonpolar solvent,the Pt ions would preferentially remain in thepolarFig.6a Average coordination numbers of Pt atoms in SiO 2supported after a sequence of hydrogen reduction and PhICl 2oxidation treatments in the toluene derived from EXAFS analysis.b The fractions of Pt(0),and Pt(II)and Pt(IV)chloride species of the dendrimer-encapsulated Pt nanoclusters derived from NEXAFS analysis(b)(c)Hydroalkoxylation reaction scheme of 2-phenylethynylphe-The evolution of Pt species in supported dendrimer-encapsu-clusters catalyst as obtained by NEXAFS measurements reaction conditions.The 2wt %Pt catalyst was oxidized byPhICl 2prior to the reaction.c Product yield as a function obtained in a batch reaction with 2wt %dendrimer encapsulated clusters loaded on mesoporous SiO 2Polymer-Encapsulated Metallic Nanoparticlesenvironment within the dendrimer,and the dendrimers would preferentially anchor on the surface of polar silica support.2.4Tuning the Catalytic Diastereoselectivityby Changing the Properties of the DendrimerMatrixDendrimer-encapsulated Pd and Pt clusters,when oxidized by PhICl2,catalyzed a range of p-bond activation.These highly active heterogeneous catalysts were generated by the reversible oxidation of metal clusters to ions,which were stabilized by the encapsulating dendrimer.In order to understand the impact of the encapsulating-matrix proper-ties on the product selectivity,dendrimer encapsulated Au nanoparticles were loaded on mesoporous silica and tested as catalysts for the multiproduct cyclopropanation reaction [29].In this reaction either cis or trans diastereomers can be formed.While employing the homogenous Au catalysts a cis:trans ratio of3.5:1was detected.However,when the homogeneous catalyst was replaced by its heterogeneous analog,the products diastereoselectivity was enhanced by ﬁve fold to16:1.It was hypothesized that the steric effect of the encapsulating matrix favors the formation of the cis isomer[51].In order to validate this hypothesis a dendri-mer matrix with lower density was synthesized and employed as an encapsulating polymer.With a less crow-ded matrix the steric effect was reduced and the cis:trans ratio deteriorated to8:1.These results demonstrate that the dendrimer matrix can impact the products distribution,in addition to its role in encapsulating and stabilizing the catalytically active nanoparticles.To take full advantage of the heterogeneous nature and high reactivity and selectivity of the dendrimer-encapsu-lated Au nanoclusters,the catalyst was packed and tested in aﬂow reactor.Importantly,the high yield and diastere-oselectivity of the dendrimer-encapsulated Au catalyst was maintained when the catalytic reaction was transferred from the batch into theﬂow mode.2.5Controlling the Products Selectivity in CascadeReactionsIn the section above we demonstrated that diastereoselec-tivity in cyclopropanation reaction can be controlled by tuning the matrix properties,which is similar to the steric effect of ligands in homogeneous catalyst.Additionally,it is also well known that in homogeneous catalysts the ligands can have a profound impact on the chemoselec-tivity.As an alternative strategy,we envisioned that che-moselectivity could be achieved with the heterogeneous system by modifying the residence time of the reactants in aﬂow reactor[29].In a cascade reaction,an intermediate can be selectively trapped by shortening the residence time, preventing its further reaction.Conversely,it may be possible to maximize the yield of theﬁnal rearrangement product by maximizing the residence time of reactants within theﬂow reactor.On the basis of this hypothesis,dendrimer-encapsulated Au catalyst was employed for the sequential cyclopropa-nation-rearrangement reaction(Fig.8).The heterogeneous nature of the Au clusters allowed the tuning of product distribution by modifying theﬂow parameters.By increasing the residence time of the reactants,both the reactivity and the selectivity towards the formation of the secondary products were enhanced.These results demon-strate the potential advantages of heterogenizing homoge-neous catalysts and highlight the unique capabilities to direct the reactivity and stereoselectivity of heterogeneous catalysts.2.6High Spatial Resolution Analysis of CascadeReaction Within a Flow ReactorCatalytic reactions alongﬂow reactors can be analyzed by a variety of spectroscopic tools,such asﬂuorescence,IR, Raman,NMR,and X-ray spectroscopy[39–42].However, these methods do not have sufﬁcient spatial or spectral resolution for detailed kinetic analysis of the catalytic reaction.In order to gain a detailed mechanistic analysis of catalytic reactions we employed synchrotron-based FTIR microspectroscopy as a tool for mapping catalytic trans-formations[52].Two nanometer sized Au nanoclusters were encapsulated within a dendrimer matrix and loaded on mesoporous SiO2support[53].The catalyst was then packed within aﬂow microreactor and its reactivity was tested toward the cascade reaction of dihydropyran for-mation(Fig.9).Propargyl vinyl ether1was catalytically rearranged by the Au catalyst to the primary product,allenic aldehyde2. Activation of the primary product by the Au catalyst was followed by nucleophilic attack of butanol-d10,which induced the formation of the secondary product,acetal3.In this cascade reaction,which was previously catalyzed by homogeneous Au complexes,each of the reactants and products show distinguishable IR signatures.As a conse-quence,the reactants-into-products evolution can be pre-cisely monitored with IR spectroscopy.At highﬂow rate(1mL/h)of the reactants(Fig.9a) only few changes were observed in the lower energy regime(1,150–2,000cm-1).A new absorption peak was detected at1,720cm-1,indicating the formation of the primary product,allenic aldehyde2.Interestingly,a max-imum in the absorption peak of the primary product was detected at0.2mm,before setting into steady absorption amplitude at0.6mm.This gradual decrease in aldehydeE.Gross et al.。

不同粒径气化细渣理化性质及燃烧特性研究

不同粒径气化细渣理化性质及燃烧特性研究不同粒径气化细渣理化性质及燃烧特性研究摘要：气化是一种高效、环保的能源利用方式，气化后的细渣也是重要的资源，然而不同粒径的细渣性质差异较大，影响其进一步应用。

本研究选取煤的不同粒径细渣为研究对象，采用傅里叶变换红外光谱（FT-IR）、X射线衍射（XRD）、扫描电子显微镜（SEM）等分析手段，研究不同粒径细渣的理化性质及燃烧特性，并探究其影响因素。

结果表明，不同粒径细渣的元素与化合物组成相似，但物化性质差异较大，小粒径细渣具有较高的比表面积和孔隙度，提高了燃烧效率和易燃性；而大粒径细渣具有较高的堆积密度和体积密度，有利于继续利用，但易结块且其燃烧特性较低。

因此，应根据实际情况选择不同粒径的细渣进行燃烧或其他应用。

关键词：气化；细渣；粒径；理化性质；燃烧特性Abstract:Gasification is an efficient and environmentally friendly way of utilizing energy, and gasification slag is also an important resource. However, theproperties of slag with different particle sizes vary greatly, which affects its further application. Inthis study, coal slag with different particle sizes was selected as the research object. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and otheranalytical methods were used to study the physical and chemical properties and combustion characteristics of slag with different particle sizes, and to exploretheir influencing factors. The results showed that the elemental and compound composition of slag with different particle sizes was similar, but there were significant differences in physical and chemical properties. Small particle size slag had higherspecific surface area and porosity, which improved combustion efficiency and flammability. However, large particle size slag had higher bulk density and volume density, which was conducive to further utilization, but was prone to agglomeration and had low combustion characteristics. Therefore, different particle size slag should be selected for combustion or other applications according to the actual situation.Keywords: Gasification; Slag; Particle size; Physical and chemical properties; Combustion characteristicIn addition to particle size, the physical andchemical properties of slag also play important roles in its utilization. The chemical composition of slag varies depending on the type of fuel and gasification technology used. For example, slag generated from biomass gasification generally has higher CaO and K2O content than that from coal gasification. These chemical components affect slag reactivity, mineralogy, and melting behavior, and therefore the potential applications.The mineralogy of slag can also impact its utilization. For instance, the presence of calcium silicates inslag can make it a potential raw material for cement production. Moreover, the melting behavior of slag determines whether it can be utilized for glass-ceramics manufacture.Besides, combustion characteristic is another critical factor affecting the utilization of slag. The combustion characteristics of slag can vary depending on the type of fuel and gasification technology. Generally, slag has a lower combustion efficiency compared to the original fuel, and combustion generates lower temperatures. The low combustion temperature makes slag not suitable for use as a heating fuel. However, with proper pretreatment,smaller particle size, and mixing with other fuels, slag can be utilized as a secondary fuel source.In conclusion, the utilization potential of slag generated from gasification depends on its physical and chemical properties, particle size, and combustion characteristics. Successful utilization of slag requires proper utilization technology and good material properties matching. Developing cost-effective and sustainable methods to utilize slag can provide environmental and economic benefitsOne promising method of utilizing slag is through its use in construction applications. As a byproduct of gasification, slag can be used as a substitute for conventional aggregates in concrete, asphalt, and other construction materials. This approach offers several benefits, including reduced environmental impact, improved durability, and cost savings.Research has shown that incorporating slag into concrete can enhance its compressive strength, reduce its permeability, and improve its durability in harsh environmental conditions. Moreover, slag has been found to have a lower environmental impact than traditional aggregates, as it produces fewer greenhouse gas emissions during production andtransport.In addition to its use in construction, slag can also be utilized as a soil amendment. As a mineral-rich material, slag can improve soil structure, increase water-holding capacity, and provide essentialnutrients for plants. This approach has been shown to be effective for both agricultural and landscaping applications and can help reduce the need forsynthetic fertilizers and other chemical additives.Overall, the utilization of slag generated from gasification offers several promising opportunitiesfor reducing waste, improving resource efficiency, and promoting environmental sustainability. While challenges remain in terms of optimizing material properties and developing effective utilization technologies, continued research and innovation inthis area are likely to yield significant benefits for both industry and the environmentOne potential application for the utilization of slag generated from gasification is in the production of construction materials such as cement and concrete. The use of slag as a partial replacement fortraditional raw materials in cement production can reduce energy consumption and greenhouse gas emissions,while also improving the durability and strength of the resulting product. This is because slag has a high content of silicates and other minerals thatcontribute to a more homogeneous and stable structure.Another potential application for slag from gasification is in the production of low-carbon fuels such as biofuels and hydrogen. By using slag as a catalyst, biomass materials can be converted into syngas, which can then be processed into a variety of fuels. In addition, slag can also be used as a medium for capturing and storing carbon dioxide emissions from industrial processes, helping to mitigate climate change.Despite the many benefits of utilizing slag from gasification, there are also several challenges that must be addressed. For example, the variability in slag composition can make it difficult to develop standardized utilization techniques. In addition, the physical properties of slag can vary widely depending on factors such as temperature, pressure, and feedstock material. This can make it difficult to predict the behavior of slag under different processing conditions, and may require additional research to optimize utilization strategies.Furthermore, the large volumes of slag that are generated by gasification processes can poselogistical challenges in terms of transport and storage. In order to fully realize the potential of slag utilization, it will be important to develop sustainable and cost-effective methods for collecting, processing, and transporting this material.Overall, the utilization of slag generated from gasification offers significant opportunities for reducing waste, improving resource efficiency, and promoting environmental sustainability. While there are challenges that must be addressed, continued research and innovation in this area are likely to yield significant benefits for both industry and the environmentIn conclusion, the utilization of slag generated from gasification presents a promising opportunity for reducing waste and promoting environmental sustainability. However, there are challenges that must be addressed, including managing the potential environmental and health risks associated with the material and developing sustainable and cost-effective methods for processing and transporting it. Further research and innovation in this area are likely toyield significant benefits for both industry and the environment。

Hard X-ray and Infrared Emission from Apparently Single White Dwarfs

The hard X-ray emission from these three apparently single WDs is illustrated in Figure 1. The ROSAT Position Sensitive Proportional Counter (PSPC) images in the 0.6–2.4 keV energy band show clearly point sources coincident with the WDs, and the PSPC spectra show distinct emission near 1 keV.
1
2
Chu et al.
Figure 1. ROSAT PSPC observations of KPD 0005+5106, PG 1159, and WD 2226−210. The top two rows show soft (0.1–0.4band images. The poor point-spread-function in the soft band is caused by an electronic ghost image at energies below 0.2 keV. The bottom row shows the PSPC spectra. To show the hard counts of PG 1159, its spectrum above 0.6 keV is scaled up by a factor of 50 as marked and plotted in open symbols.
arXiv:astro-ph/0701025v1 1 Jan 2007
**FULL TITLE** ASP Conference Series, Vol. **VOLUME**, **YEAR OF PUBLICATION** **NAMES OF EDITORS**

工控常用英文缩写

工控常用英文缩写AC(alternating current) 交流(电)A／D(analog to digital) 模拟／数字转换ADC(analog to digital convertor) 模拟／数字转换器ADM(adaptive delta modulation) 自适应增量调制ADPCM(adaptive differential pulse code modulation) 自适应差分脉冲编码调制ALU(arithmetic logic unit) 算术逻辑单元ASCII(American standard code for information interchange) 美国信息交换标准码A V(audio visual) 声视，视听BCD(binary coded decimal) 二进制编码的十进制数BCR(bi-directional controlled rectifier)双向晶闸管BCR(buffer courtier reset) 缓冲计数器BZ(buzzer) 蜂鸣器，蜂音器C(capacitance，capacitor) 电容量，电容器CA TV(cable television) 电缆电视CCD(charge-coupled device) 电荷耦合器件CCTV(closed-circuit television) 闭路电视CMOS(complementary) 互补MOSCPU(central processing unit)中央处理单元CS(control signal) 控制信号D(diode) 二极管DAST(direct analog store technology) 直接模拟存储技术DC(direct current) 直流DIP(dual in-line package) 双列直插封装DP(dial pulse) 拨号脉冲DRAM(dynamic random access memory) 动态随机存储器DTL(diode-transistor logic) 二极管晶体管逻辑DUT(device under test) 被测器件DVM(digital voltmeter) 数字电压表ECG(electrocardiograph) 心电图ECL(emitter coupled logic) 射极耦合逻辑EDI(electronic data interchange) 电子数据交换EIA(Electronic Industries Association) 电子工业联合会EOC(end of conversion) 转换结束EPROM(erasable programmable read only memory) 可擦可编程只读存储器EEPROM(electrically EPROM) 电可擦可编程只读存储器ESD(electro-static discharge) 静电放电FET(field-effect transistor) 场效应晶体管FS(full scale) 满量程F／V(frequency to voltage convertor) 频率／电压转换FM(frequency modulation) 调频FSK(frequency shift keying) 频移键控FSM(field strength meter) 场强计FST(fast switching shyster) 快速晶闸管FT(fixed time) 固定时间FU(fuse unit) 保险丝装置FWD(forward) 正向的GAL(generic array logic) 通用阵列逻辑GND(ground) 接地，地线GTO(Sate turn off thruster) 门极可关断晶体管HART(highway addressable remote transducer) 可寻址远程传感器数据公路HCMOS(high density COMS) 高密度互补金属氧化物半导体(器件)HF(high frequency) 高频HTL(high threshold logic) 高阈值逻辑电路HTS(heat temperature sensor) 热温度传感器IC(integrated circuit) 集成电路ID(international data) 国际数据IGBT(insulated gate bipolar transistor) 绝缘栅双极型晶体管IGFET(insulated gate field effect transistor) 绝缘栅场效应晶体管I／O(input／output) 输入／输出I／V(current to voltage convertor) 电流-电压变换器IPM(incidental phase modulation) 附带的相位调制IPM(intelligent power module) 智能功率模块IR(infrared radiation) 红外辐射IRQ(interrupt request) 中断请求JFET(junction field effect transistor) 结型场效应晶体管LAS(light activated switch)光敏开关LASCS(light activated silicon controlled switch) 光控可控硅开关LCD(liquid crystal display) 液晶显示器LDR(light dependent resistor) 光敏电阻LED(light emitting diode) 发光二极管LRC(longitudinal redundancy check) 纵向冗余(码)校验LSB(least significant bit) 最低有效位LSI(1arge scale integration) 大规模集成电路M(motor) 电动机MCT(MOS controlled gyrator) 场控晶闸管MIC(microphone) 话筒，微音器，麦克风min(minute) 分MOS(metal oxide semiconductor)金属氧化物半导体MOSFET(metal oxide semiconductor FET) 金属氧化物半导体场效应晶体管N(negative) 负NMOS(N-channel metal oxide semiconductor FET) N沟道MOSFETNTC(negative temperature coefficient) 负温度系数OC(over current) 过电流OCB(overload circuit breaker) 过载断路器OCS(optical communication system) 光通讯系统OR(type of logic circuit) 或逻辑电路OV(over voltage) 过电压P(pressure) 压力FAM(pulse amplitude modulation) 脉冲幅度调制PC(pulse code) 脉冲码PCM(pulse code modulation) 脉冲编码调制PDM(pulse duration modulation) 脉冲宽度调制PF(power factor) 功率因数PFM(pulse frequency modulation) 脉冲频率调制PG(pulse generator) 脉冲发生器PGM(programmable) 编程信号PI(proportional-integral(controller)) 比例积分(控制器)PID(proportional-integral-differential(controller))比例积分微分(控制器) PIN(positive intrinsic-negative) 光电二极管PIO(parallel input output) 并行输入输出PLD(phase-locked detector) 同相检波PLD(phase-locked discriminator) 锁相解调器PLL(phase-locked loop) 锁相环路PMOS(P-channel metal oxide semiconductor FET) P沟道MOSFETP-P(peak-to-peak) 峰--峰PPM(pulse phase modulation) 脉冲相位洲制PRD(piezoelectric radiation detector) 热电辐射控测器PROM(programmable read only memory) 可编只读程存储器PRT(platinum resistance thermometer) 铂电阻温度计PRT(pulse recurrent time) 脉冲周期时间PUT(programmable unijunction transistor) 可编程单结晶体管PWM(pulse width modulation) 脉宽调制R(resistance，resistor) 电阻，电阻器RAM(random access memory) 随机存储器RCT(reverse conducting thyristor) 逆导晶闸管REF(reference) 参考，基准REV(reverse) 反转R/F(radio frequency) 射频RGB(red／green／blue) 红绿蓝ROM(read only memory) 只读存储器RP(resistance potentiometer) 电位器RST(reset) 复位信号RT(resistor with inherent variability dependent) 热敏电阻RTD(resistance temperature detector) 电阻温度传感器RTL(resistor transistor logic) 电阻晶体管逻辑(电路)RV(resistor with inherent variability dependent on the voltage) 压敏电阻器SA(switching assembly) 开关组件SBS(silicon bi-directional switch) 硅双向开关，双向硅开关SCR(silicon controlled rectifier) 可控硅整流器SCS(safety control switch) 安全控制开关SCS(silicon controlled switch) 可控硅开关SCS(speed control system) 速度控制系统SCS(supply control system) 电源控制系统SG(spark gap) 放电器SIT(static induction transformer) 静电感应晶体管SITH(static induction thyristor) 静电感应晶闸管SP(shift pulse) 移位脉冲SPI(serial peripheral interface) 串行外围接口SR(sample realy，saturable reactor) 取样继电器，饱和电抗器SR(silicon rectifier) 硅整流器SRAM(static random access memory) 静态随机存储器SSR(solid-state relay) 固体继电器SSR(switching select repeater) 中断器开关选择器SSS(silicon symmetrical switch) 硅对称开关，双向可控硅SSW(synchro-switch) 同步开关ST(start) 启动ST(starter) 启动器STB(strobe) 闸门，选通脉冲T(transistor) 晶体管，晶闸管TACH(tachometer) 转速计，转速表TP(temperature probe) 温度传感器TRIAC(triodes AC switch) 三极管交流开关TTL(transistor-transistor logic) 晶体管一晶体管逻辑TV(television) 电视UART(universal asynchronous receiver transmitter) 通用异步收发器VCO(voltage controlled oscillator) 压控振荡器VD(video decoders) 视频译码器VDR(voltage dependent resistor) 压敏电阻VF(video frequency) 视频V／F(voltage-to-frequency) 电压／频率转换V／I(voltage to current convertor) 电压-电流变换器VM(voltmeter) 电压表VS(vacuum switch) 电子开关VT(visual telephone) 电视电话VT(video terminal) 视频终端pH计pH meterX射线衍射仪X-ray diffractometerX射线荧光光谱仪X-ray fluorescence spectrometer力测量仪表force measuring instrument孔板orifice plate文丘里管venturi tube水表water meter加速度仪accelerometer可编程序控制器programmable controller平衡机balancing machine皮托管Pitot tube皮带秤belt weigher光线示波器light beam oscillograph光学高温计optical pyrometer光学显微镜optical microscope光谱仪器optical spectrum instrument吊车秤crane weigher地中衡platform weigher字符图形显示器character and graphic display位移测量仪表displacement measuring instrument巡?检测装置data logger波纹管bellows长度测量工具dimensional measuring instrument长度传感器linear transducer厚度计thickness gauge差热分析仪differential thermal analyzer扇形磁场质谱计sector magnetic field mass spectrometer 料斗秤hopper weigher核磁共振波谱仪nuclear magnetic resonance spectrometer 气相色谱仪gas chromatograph浮球调节阀float adjusting valve真空计vacuum gauge动圈仪表moving-coil instrument基地式调节仪表local-mounted controller密度计densitometer液位计liquid level meter组装式仪表package system减压阀pressure reducing valve测功器dynamometer紫外和可见光分光光度计ultraviolet-visible spectrometer 顺序控制器sequence controller微处理器microprocessor温度调节仪表temperature controller煤气表gas meter节流阀throttle valve电子自动平衡仪表electronic self-balance instrument电子秤electronic weigher电子微探针electron microprobe电子显微镜electron microscope弹簧管bourdon tube数字式显示仪表digital display instrument热流计heat-flow meter热量计heat flux meter热电阻resistance temperature热电偶thermocouple膜片和膜盒diaphragm and diaphragm capsule 调节阀regulating valve噪声计noise meter应变仪strain measuring instrument湿度计hygrometer声级计sound lever meter黏度计viscosimeter转矩测量仪表torque measuring instrument转速测量仪表tachometer露点仪dew-point meter变送器transmitter。

X射线衍射和小角X射线散射

晶体的X射线衍射特征
[Crystal Structure Analysis, 3rd Edition, p. 48]
晶体结构及其晶胞类型
[Methods of Experimental Physics Volume 16: Polymers, Part B Crystal Structure and Morphology, p. 5]
X射线衍射需要在广角范围内测定，因此又被称为广角X射线衍射（Wide-Angle X-ray Scattering, WAXS）。
小角X射线散射
如果被照射试样具有不同电子密度的非周期性结构，则次生X射线不会发生干涉现象，该现象被称为漫射X射线衍射（简称散射）。
X射线散射需要在小角度范围内测定，因此又被称为小角X射线散射（Small-Angle Xray Scattering, SAXS）。
晶面指数与晶胞参数
[Fundamentals of Powder Diffraction and Structural Characterization of Materials, 2nd Edition, p. 9]
Bragg方程
设晶体的晶面距为 d，X射线以与晶面间交
角为的方向照射，从晶面散射出来的X射
粉末衍射条纹摄制及处理
[Fundamentals of Powder Diffraction and Structural Characterization of Materials, 2nd Edition, p. 265]
粉末衍射平板图案摄制
[Fundamentals of Powder Diffraction and Structural Characterization of Materials, 2nd Edition, p. 153]

第四章 X射线衍射与散射

（2）特征X．Ray：由靶的原子序数决定。当高速电子流冲击在阳极物质上，把其内层电子击出，此时原子总能量升高，原子外层电子跃入内层填补空位，由于位能下降而发射出X．Ray。K层产生空位后，L层迁入几率最大，产生的X．Ray称为Kα；因L层有三个不同能量级，由量子力学选择定则有两个能量级电子允许迁入K层，故Kα由Kα1和Kα2组成，Kα1 =2Kα2，Kα1 =Kα20.004nm；当分辨率低时两者分不开，则：
干涉指数与晶面指数的明显差别是干涉指数中有公约数，而晶面指数只能是互质的整数，当干涉指数也互为质数时，它就代表一族真实的晶面，所以干涉指数是
广义的晶面指数。习惯上经常将HKL混为hkl来讨论问题。
我们设d=dˊ/n，布拉格方程可以写成： 2dsinθ=λ
3 布拉格方程的应用
上述布拉格方程在实验上有两种用途。首先，利用已知波长的特征X射线，通过测量θ角，可以计算出晶面间距d。这种工作叫结构分析（structure analysis）,是本书所要论述的主要内容。其次，利用已知晶面间距d的晶体，通过测量θ角，从而计算出未知X射线的波长。后一种方法就是X射线光谱学（X-ray spectroscopy）。
(a)
(b)
(c)
(d)
(4) 作用从多晶照相可以获知试样中结晶状况。对试样中有无结晶，晶粒是否择优取向，取向程度等进行定性判断。因此，多晶照相底片成为直观定性判断试样结晶状况的简明实证。通过照相底片还可对聚集态结构进行定量分析，但这部分工作已为后来发展起来的衍射取代。实际中，因Derby照相较平板照相简便、灵活，且误差小，所以大都采用Derby照相.
周转晶体法
三.粉末法
粉末法用单色的X射线照射多晶体试样，利用晶粒的不同取向来改变θ，以满足布拉格方程。

X射线的种类及应用

X射线的种类及应用摘要：Like many imperishable discoveries,X-rays’s invention or discovery was accidental. 1895 at Wurzburg, Wilhelm Rontgen discovered X-rays (Rontgen rays). After all these years, the technology of the X-rays has not only got extensivedevelopment in industry, also play a more and more important role in medical science. It is mainly used for the human body perspective and check injury. While scientists explore the essence of，they found the phenomenon of diffraction of X-rays and opened the gate of the crystal structure. With the widely use of x-ray both in micro fields and macro fields, it have brought great gospel to human.引言：自1895年X射线被发现，X射线已被广泛应用到医疗卫生、军事、科学及工农业各方面，为人类社会的发展做出了巨大贡献。

在X射线自从发现以来，医学就成为其主要应用，经过近百年的发展，X射线技术已广泛的应用于医学影像诊断，成为医学临床和科研不可或缺的因素。

本文就X射线的分类以及X射线的主要运用展开论述。

具体内容如下：内容X射线是一种波长很短的电磁辐射，其波长约为（20～0.06）×10-8厘米之间，又称伦琴射线。

无线电通信原理第三章(英文)

df
2D2
d f D and d f
• To be in the far-field region, d must satisfy
d df
2020/7/18
10
The Reference Distance
• It is clear that equation does not hold for d=0. For this reason, large-
infrared visible light UV
VLF = Very Low Frequency , LF = Low Frequency , MF = Medium Frequency , HF = High Frequency , VHF = Very High Frequency, UHF = Ultra High
2020/7/18
3
Spectrum twisted
coax cable
pair
optical transmission
1 Mm 300 Hz
10 km 30 kHz
100 m 3 MHz
1m 300 MHz
10 mm 30 GHz
100 m 3 THz
1 m 300 THz
VLF
LF MF HF VHF UHF SHF EHF
• The path loss for the free space model when antenna gains are included is given by quantity measured in dB, is defined as the
PL(dB) 10log
Pt Pr
10
log[
2020/7/18

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

a r X i v :a s t r o -p h /0408087v 1 4 A u g 2004Astronomy &Astrophysics manuscript no.(will be inserted by hand later)Infrared and X–ray variability of the transient Anomalous X-rayPulsar XTE J1810-197⋆N.Rea 1,2,V.Testa 2,G.L.Israel 2,3,S.Mereghetti 4,R.Perna 5,L.Stella 2,3,A.Tiengo 4,6,V.Mangano 7,T.Oosterbroek 8,R.Mignani 9,G.Lo Curto 10,S.Campana 11,S.Covino 111Universit´a di Roma 2,Via della Ricerca Scientiﬁca 1,I–00133Roma,Italy:rea@mporzio.astro.it 2INAF–Osservatorio Astronomico di Roma,Via Frascati 33,I–00040Monteporzio Catone,Italy 3Aﬃliated with International Center for Relativistic Astrophysics4CNR-IASF,Sezione di Milano “G.Occhialini”,Via Bassini 15,I–20133Milano,Italy 5Department of Astrophysical Sciences,Princeton University,Princeton,NJ 085446Universit`a degli Studi di Milano,Dipartimento di Fisica,v.Celoria 16,I-20133Milano,Italy 7CNR-IASF,Sezione di Palermo,Via Ugo La Malfa 153,I–90146Palermo,Italy8Astrophysics Missions Division,Research and Scientiﬁc Support Department of ESA,ESTEC,Postbus 299,NL-2200AG Noordwijk,Netherlands9European Southern Observatory,Karl–Schwarzschild str.2,D–85748Garching,Germany10European Southern Observatory,Av.Alonso de Cordova 3107,Vitacura,Casilla 19001,Santiago 19,Chile 11INAF –Osservatorio Astronomico di Brera,Via Bianchi 46,I–23807Merate (Lc),ItalyAbstract.We report on observations aimed at searching for ﬂux variations from the proposed IR counterpart of the Anomalous X–ray Pulsar (AXP)XTE J1810−197.These data,obtained in March 2004with the adaptive optics camera NAOS-CONICA at the ESO VLT,show that the candidate proposed by Israel et al.(2004)was fainter by ∆H =0.7±0.2and ∆K s =0.5±0.1with respect to October 2003,conﬁrming it as the IR counterpart of XTE J1810−197.We also report on an XMM–Newton observation carried out the day before the VLT observations.The 0.5-10keV absorbed ﬂux of the source was 2.2×10−11erg cm −2s −1,which is less by a factor of about two compared to the previous XMM–Newton observation on September 2003.Therefore,we conclude that a similar ﬂux decrease took place in the X–ray and IR bands.We brieﬂy discuss these results in the framework of the proposed mechanism(s)responsible for the IR variable emission of AXPs.1.IntroductionThe X-ray source XTE J1810−197was discovered in July 2003as a transient pulsar with a ﬂux of ∼5×10−11erg cm −2s −1and a period of 5.5s (Ibrahim et al.2004;Markwardt et al.2003).Already from the ﬁrst RXTE and Chandra results it clearly appeared that the properties of XTE J1810−197are diﬀerent from those of the majority of X-ray transient pulsars.The latter are easily identiﬁed as neutron stars accreting from compan-ion stars.On the other hand the long term spin-down at ∼10−11ß,the soft X-ray spectrum,and the upper lim-its on its optical counterparts indicated XTE J1810−197as a likely member of the class of Anomalous X-ray Pulsars (AXPs,see Mereghetti et al.2002and Woods &Thompson 2004for a review).The AXP nature of XTE J1810−197was further strengthened by an XMM-Newton observation (Tiengo &Mereghetti 2003;Gotthelf et al.2Rea et al.:IR and X-ray variability of XTE J1810−197 scenarios are discussed by several authors and not com-pletely ruled out.For example several models based onaccretion from residual disks around isolated neutronstars have been proposed(Alpar2001;Perna et al.2000;Chatterjee et al.2000).The particular interest for XTE J1810−197lies inits transient nature,as testiﬁed by archival observationsshowing a luminosity a factor∼100below that observedin2003-2004.In fact,most AXP have shown until re-cently little or no long term variability1.The results onXTE J1810−197imply the existence of a,possibly large,population of quiescent AXPs in the Galaxy,with rele-vant implications on the nature and evolution of theseobjects.Recent observations have also revealed variationsin the X-rayﬂux of a few”persistent”AXPs(Kaspi etal.2003;Mereghetti et al.2004;Gavriil&Kaspi2004),as well as in their infrared counterparts(see Israel et al.2004a).However,a clear picture of these variability prop-erties has still to emerge.In this context,multi-wavelengthmonitoring of XTE J1810−197,the only conﬁrmed tran-sient AXP,can yield interesting results.Here we reporton nearly simultaneous X-ray and IR observations of XTEJ1810−197,showing aﬂux decrease in both bands whichconﬁrms the proposed IR identiﬁcation.2.Data analysis and resultsDeep IR imaging was obtained at the VLT-UT4Yepunwith the Nasmith Adaptive Optics System and the HighResolution Near IR Camera(NAOS-CONICA)on2004March12,13and14.The pixel size of the camera is0.027′′.Images were reduced with the instrument-speciﬁcpipelines and checked by reducing them again with thesoftware package eclipse.A total of18cube images in Ksand26in H,of40s exposure each,were obtained,for atotal exposure time of36and52minutes in Ks and H,respectively.The on-axis FWHM was determined to be0.09′′(3.3pixels)in K s and0.10′′(3.6pixels)in H.Aperture photometry was performed with the digiphotpackage of IRAF2.The two output catalogs were matchedand calibrated by using a set of secondary standards intheﬁeld,for which magnitudes and colors were alreadyobtained in October2003(Israel et al.2004).We found thefollowing IR magnitudes for the proposed IR counterpart:K s=21.36±0.07and H=22.73±0.18.The objectwas not detected in the J band(J>23.0,3σu.l.).Thecorresponding values in October2003were K s=20.8±0.1and H=22.0±0.1.As shown in Fig.1,where the diﬀerence between themagnitudes in October2003and March2004are plottedRea et al.:IR and X-ray variability of XTE J1810−19730.01keV and photon index of Γ=3.8±0.1(χ2ν=1.15;uncertainties are at 90%conﬁdence level;see Fig.2).The corresponding blackbody radius was 1.23±0.02km,for an assumed distance of 4kpc (the estimated distance is 3–5kpc;Gotthelf et al.2004).The 0.5-10keV absorbed ﬂux was (2.2±0.1)×10−11erg cm −2s −1,corresponding to an unabsorbed ﬂux of 8.2×10−11erg cm −2s −1.The black-body component accounts for the 60%of the absorbed ﬂux in the 0.5-10keV band.An equally acceptable ﬁt (χ2ν=1.23)was also ob-tained keeping the absorption ﬁxed at the September 2003value (1.05×1022atoms cm −2;Tiengo &Mereghetti 2003,Gotthelf et al.2004).The resulting spectral parameters were kT=0.68±0.01keV and Γ=4.1±0.1.Using two blackbodies to ﬁt the spectra we found:N H =0.58±0.02×1022atoms cm −2,kT 1=0.29±0.01keV (radius of 5.1±0.6km)and kT 2=0.70±0.01keV (radius of 1.21±0.04km;χ2ν=1.17).The ﬁrst blackbody had a 0.5-10keV absorbed ﬂux of 3.9×10−12erg cm −2s −1(18%of the total ﬂux)and the sec-ond of 1.8×10−11erg cm −2s −1.Further analysis of the XMM-Newton observations,including phase resolved spectroscopy,will be reportedelsewhere.Fig.2.Broadband energy spectrum of XTE J1810−197.Filled squares represent the 2004XMM-Newton PN and VLT-NACO observations while triangles are relative to the 2003observations.Moreover ﬁlled stars represent the spectrum of the ROSAT 1992observation.Reported IR ﬂuxes are absorbed and unabsorbed.3.DiscussionOur new diﬀraction limited VLT images of the XTE J1810−197ﬁeld,carried out six months after the previous ones,clearly show a decrease in the IR ﬂux of the candi-date previously proposed based only on positional coinci-dence and unusual colors (Israel et al.2004).This ﬁnding conﬁrms it as the IR counterpart of XTE J1810−197,which showed during the same period a similar variation in its X–ray ﬂux.The only other case of correlated X-ray and IR ﬂux variations in an AXP observed to date was found after the detection of a series of short bursts from 1E 2259+586(Kaspi et al.2003).In this case the X-ray and IR ﬂuxes decreased by a factor less than two in about one week.The X–ray pulse shape,the pulsed fraction and the spectral parameters changed signiﬁcantly (Woods et al.2003),and a glitch was also observed.The X-ray and IR variability reported here for XTE J1810−197is not obviously tied to bursting activity from the source (although the occurrence of bursts before the observation,or at the time of the start of the outburst between November 2002and January 2003,cannot beexcluded).Fig.3.Resulting correlation between X-ray and IR lumi-nosity from a disk (assuming a typical 60deg inclination of the disk and a distance of ∼5kpc).Contrary to the case of 1E 2259+586,we do not see large variations in the timing or spectral properties of XTE J1810−197between the two XMM-Newton obser-vations.There is only some evidence for a moderate soft-ening of the X–ray spectrum,as indicated by the change of the photon index from 3.7±0.2(Gotthelf et al.2004)to 4.1±0.2(for the blackbody plus power-law model ﬁts with a constant absorption).Comparing the X-ray outburst of XTE J1810−197with that recently found in another AXP,1E 1048.1−5937(Gavriil &Kaspi 2004),we noticed that in both cases the corresponding ﬂuences are of the order of few 1042erg s −1.Moreover,looking at the published decaying lightcurves for XTE J1810−197and 1E 1048.1−5937(Ibrahim et al.2004;Gavriil &Kaspi 2004),it is evident the similarity of the decaying law behaviour,suggesting that both out-bursts obay to the same physical process.The IR emission from AXP in the context of the mag-netar model has been recently discussed by ¨Ozel (2004),who noticed that the IR emission cannot be due to ther-mal emission from the neutron star surface and is consis-4Rea et al.:IR and X-ray variability of XTE J1810−197tent with synchrotron emission in the magnetosphere.The value of the IR to X–rayﬂux ratio we derived for XTE J1810−197,when plotted versus the neutron star spin down luminosity,does not follow the trend of the other AXPs shown in Fig.3of¨Ozel(2004).However,for what concerning the other possibility proposed by¨Ozel(2004) in which the magnetospheric emission is powered by the magnetic energy,no quantitative predictions are reported therefore we cannot exclude this possibility.The somehow correlated IR/X-rayﬂuxes of XTE J1810-197can be accounted for in a“hybrid”model of a magnetar surrounded by a fossil disk(Eksi&Alpar2003). The spectral characteristics of fall-back disks around iso-lated neutron stars were studied in detail by Perna et al. (2000)and Perna&Hernquist(2000).They considered the contribution to the emission from both viscous dissi-pation and reprocessing of the X-ray luminosity from the star,ﬁnding that the long wavelength emission,and in par-ticular the IR,is dominated by reprocessing of the X-ray radiation(presumably coming from a magnetar).This im-mediately implies that X-ray and IRﬂux variations must be correlated.We studied the extent of this correlation for an X-ray luminosity on the order of a few×1034erg s−1(assuming here a distance of5kpc)and for a disk model as described in the references above.We found(see Fig.3)that a vari-ation in X-ray luminosity of the star by a factor of∼2 results in a corresponding variation of the IRﬂux from the disk by also a factor of2,and the intensity of the predicted IRﬂux is also consistent with the observations(assuming a typical60◦inclination of the disk).These results are largely independent of the inner and outer radius of the disk,as the IR emission is produced in a small ring which, for the range of X-ray luminosities under consideration is at a distance of a few×1010−1011cm.In this scenario we expect L IR and L X to be corre-lated,even if not linearly.This is due to the fact that, as L X increases,the overall temperature in the disk con-sequently increases,and the region with temperatures at which the IR radiation is produced moves towards larger radii.This results in a larger emission area.On the other hand,as L X decreases,theﬂux from the disk becomes gradually more dominated by viscous dissipation up to a point where this completely takes over and L IR becomes independent of L X:however the L X limit value for the reprocessing dominated IR emission is largely lower than the typical AXPs X-ray luminosity,we then conclude that in the AXPs case the IR emission is almost completely due to the X-ray reprocessing phenomenon.By consider-ing the AXPs sample as a whole,we would expect that X-ray brighter objects would generally have brighter IR counterparts.Indeed,this has been hinted at by Hulleman et al.(2004).Our suggestion can be tested by a search for pulsations in the IR radiation similarly to the search that Kern& Martin(2002)performed in the optical.ReferencesAlpar,M.A.,2001,ApJ,554,1245Chatterjee,P.,Hernquist,L.&Narayan,R.,2000,ApJ,534, 373Duncan,R.C.,&Thompson,C.1992,ApJ,392,L9Eksi&Alpar2003,ApJ,599,450Gotthelf,E.V.et al.2001,AIPC,599,445Gotthelf,E.V.,Halpern,J.P.,Buxton,M.&Bailyn,C.,2004, ApJ,605,368Gavriil,F.P.,Kaspi,V.M.,&Woods,P.M.2002,Nature,419, 142GGavriil, F.P.&Kaspi,V.M.2004,ApJ Letters, astro-ph/0404113Hulleman, F.,van Kerkwijk,M.H.&Kulkarni,S.R.2004, A&A,416,1037Hurley2000,AIPC,526,763HIbrahim,I.A.,et al.2004,ApJL,609,L21Israel,G.L.,Rea,N.,Mangano,V.,Testa,V.,Perna,R., Hummel,W.,Mignani,R.,et al.2004,ApJL,603,L97 Israel et al.2004a,IAU Symposium218Proceedings, astro-ph/0310482Kaspi,V.M.,Gavriil,F.P.,Woods,P.M.,Jensen,J.B.,Roberts, M.S.E.&Chakrabarty D.2003,ApJL,588,L93Kaspi,V.M.,et al.2004,Astronomer’s Telegram#298 Kern,B.&Martin,C.2002,Nature,417,527Markwardt,C.B.,Ibrahim,A.I.,Swank,J.H.2003,IAU Circ.8168Mereghetti,S.,&Stella,L.1995,ApJ,442,L17 Mereghetti,S.,Chiarlone,L.,Israel,G.L.,Stella,L.2002,MPE Rep,278;Garching:MPE,29Mereghetti,S.,Tiengo,A.,Stella L.,Israel G.L.,Rea,N.,Zane, S.,Oosterbroek,T.2004,ApJ,608,427¨Ozel,F.,2004,astro-ph/0404144,submitted to ApJL Perna,R.,Hernquist,L.&Narayan,R.2000,ApJ,541,344 Perna,R.&Hernquist,L.2000,ApJ,544,L57Stetson,P.B.1990,PASP,102,932Str¨u der,L.,et al.2001,A&A,365,L18Thompson,C.,&Duncan,R.C.1995,MNRAS,275,255 Tiengo A.&Mereghetti S.2003,Astronomer’s Telegram#193 Turner,M.J.L.,et al.2001,A&A,365,L27van Paradijs,J.,Taam R.E.&van den Heuvel E.P.J.,1995, A&A,299,L41Woods,P.,Kaspi,V.M.,Thompson,C.,Gavriil,F.,Marshall,H.L.,Chakrabarty,D.,et al.2004,ApJ,605,378 Woods,P.&Thompson,C.2004,astro-ph/0406133。