uv-vis2012简化版
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400
λmin λmin 600
500
λ(nm)
浓度 T: transmittance 透光率
Designed by Amy. L
§2. Absorption law
Io= Ia + It + Ir
using same absorption cell
I0 Ir It
law 定律 cell 吸收池 incident light 入射光 reflected fl d li light h 反射光 transmitted light 透射光 transmittance 透光率 absorbance 吸光度
C1
<
C2
<
C3
<
C4
<
C5
C↑, color is thicker Cx Colorimetric techniques: detector : human eyes
k is a characteristic value of particular substance at a given λ, at certain T and in certain solution. 2+
of light will be weaken
Designed by Amy. L
The color seen is the complementary color of the color absorbed
Potassium permanganate (KMnO4)
wavelength 波长 frequency 频率 Plank constant 普郎克常数 nanometer 纳米
9 1 Cu : 1s22s22p63s23p63d10 4s 2+
Usage: selecting a wavelengh suitable for quantitative analysis
508
A： absorbance 吸光度 spectrum 光谱
concentration
The outer shell of the contains an odd unpaired electron. Organic substances: unsaturated compounds Those carrying a double bond are often colored, especially when the double bond is between carbon an element other than carbon. O nitro-compounds containing the group —C — NO
cause a change in direction of the beam at the sample interphase.
III. Basic principle:
wave-particle nature E = h = h c/λ wavelength: λ (nm) frequency: (s-1)
150~400
200~350
tungsten 钨 filament 灯丝
collimating mirror
slit
deuterium
氘
dispersion
dispersion
focus
slit
Designed by Amy. L
focusing mirror
slit
3
aluminized surface
IV. Molecular Absorption Spectroscopy
1. Birth of molecular absorption spectroscopy
* Three states of movement
1) Electrons move around the nuclear----- En 2) Two or more atoms vibrate --------------- Vn 3) Treat the molecule as a whole, spin------- rn
Designed by Amy. L
1
High
E2
v4 v2 v0
E2 *Energy level diagram
v0
v4 v2 Energy E1 v0 v4 v2 Low
*Energy level transition
E1 v0
r3 r1
v4 v2
r3 r1
E0 v0
En: be subdivided into a number of Vn(Vibraional sublevels) Vn: be subdivided into a number of rn (rotational sublevels)
350~750 T: 2400-3000K I ∝ V4
Designed by Amy. L
1. light source: 200-750nm Over the entire wavelength range of interest: continuous, high intensity , stable and long life *Hydrogen/deuterium lamp
Io= Ia + It
b: path length ( cm) c:concentration(<0.01mol/L) k: absorptivity; absorption capability for a particular substance When a beam of parallel monochromatic light pass through a cell of solution, A is proportion to the production of b and c.
back
120nm-60μm
1 cm 0.5cm 2 cm 3 cm
Littrow prism x nm-xxxμm
dispersion
>100 grooves/mm 4000 grooves/mm
Materials: *glass: can be used down to about 320nm, or will absorb most of the radiation. *quartz: can be used under or above 320nm, more expensive.
Designed by Amy. L
II. Lambert - Beer law
A = -lgT=lg I0 / It = kbc
I0 c b It
path length 路径长度 concentration 浓度 absorptivity 吸光系数 characteristic value 特征值 monochromatic 单色的 transparent 透明的 production 乘积
c = 3*108m.s-1 h = 6.63*10-34J.s-1 1nm=10-9m
wavelength 波长 frequency 频率 Plank constant 普郎克常数 nanometer 纳米
UV： 200-400nm VIS： 400-750nm
Designed by Amy. L
λ(nm) λ(nm) often used
2. Monochromator: slit
collimation
monochromator 单色器 slit 狭缝 collimation 准直, 校正平行 ispersion 色散元件 focus 聚焦 concave mirror 凹面镜
Designed by Amy. L
2. Monochromator: slit
collimation
3. Absorption cell:
prism 棱镜 refraction 折射 grating 光栅 groove 刻槽 interference 干涉 diffraction 衍射 holograph 全息照相
Designed by Amy. L
2. Absorption curve/spectrum
A
λmax
Na : 1s22s22p63s1
+
Ions have inert gas structure ( an even number of electrons), each electron paired with one of opposite spin direction. CuCl2 : blue/green
continuous, high intensity , stable and long life *Tungsten filament lamp
λ(nm) ( )
tungsten 钨 filament 灯丝
λ( (nm) ) often used
deuterium
氘
350~2000
light source mono chromator absorption cell detector indicator
I. Transmittance (T)& Absorbance(A)
T = It / I0 A=-lgT=lg I0 / It 0% ~ 100%
0 ~ ∞
Designed Designed by Amy. by Amy. L L
2
III. Key Point
A=-lgT=lg I0 / It A = k (ε, a ) bc Notice: c (mol.L-1) k: ε (L.mol-1.cm-1) c (g.L-1) k: a (L.g-1.cm-1)
identify 鉴别 qualitative 定性的 quantitative 定量的 absorption 吸收 radiation 辐射 molecule 分子
Designed by Amy. L
Designed by Amy. L
II. Terms:
beam 光束 emission photon 光子 sample sample emission reflection 发射 refraction reflection th process of the f a photon h t b being i emitted itt d 反射 scattering by solid impurity particles refraction 折射 absorption 吸收 radiation sample 辐射 absorption transmission along radiation beam, intensity transmission 透射
(525nm)
manganese(Mn )ε 0.02 (525nm)
k stands for the sensitivity. permanganateL(MnO -) ε 2×103 4
§4. UV-VIS Spectrophotometer I. Major component
Types
1. light source: 200-750nm Over the entire wavelength range of interest:
E0
Electronic transition
Vibrational transition
Rotational transition
v0
*Conclusion:
Absorption of light is due to the transition of electrons from low to high energy levels Inorganic substances: presence of unpaired electrons NaCl : colorless
UV-VIS SPECTROPHOTOMETRY
ultraviolet 紫外的 visible 可见的 p spectrophotometry 分光光度法
§1. Introduction
I. UV-VIS spectrophotometry:
A kind of analytical method to identify chemical species (qualitative analyses) and determine the amount of a particular species (quantitative analyses). This method is based on measuring the absorption of UV or visible radiation by molecules. molecules
λmin λmin 600
500
λ(nm)
浓度 T: transmittance 透光率
Designed by Amy. L
§2. Absorption law
Io= Ia + It + Ir
using same absorption cell
I0 Ir It
law 定律 cell 吸收池 incident light 入射光 reflected fl d li light h 反射光 transmitted light 透射光 transmittance 透光率 absorbance 吸光度
C1
<
C2
<
C3
<
C4
<
C5
C↑, color is thicker Cx Colorimetric techniques: detector : human eyes
k is a characteristic value of particular substance at a given λ, at certain T and in certain solution. 2+
of light will be weaken
Designed by Amy. L
The color seen is the complementary color of the color absorbed
Potassium permanganate (KMnO4)
wavelength 波长 frequency 频率 Plank constant 普郎克常数 nanometer 纳米
9 1 Cu : 1s22s22p63s23p63d10 4s 2+
Usage: selecting a wavelengh suitable for quantitative analysis
508
A： absorbance 吸光度 spectrum 光谱
concentration
The outer shell of the contains an odd unpaired electron. Organic substances: unsaturated compounds Those carrying a double bond are often colored, especially when the double bond is between carbon an element other than carbon. O nitro-compounds containing the group —C — NO
cause a change in direction of the beam at the sample interphase.
III. Basic principle:
wave-particle nature E = h = h c/λ wavelength: λ (nm) frequency: (s-1)
150~400
200~350
tungsten 钨 filament 灯丝
collimating mirror
slit
deuterium
氘
dispersion
dispersion
focus
slit
Designed by Amy. L
focusing mirror
slit
3
aluminized surface
IV. Molecular Absorption Spectroscopy
1. Birth of molecular absorption spectroscopy
* Three states of movement
1) Electrons move around the nuclear----- En 2) Two or more atoms vibrate --------------- Vn 3) Treat the molecule as a whole, spin------- rn
Designed by Amy. L
1
High
E2
v4 v2 v0
E2 *Energy level diagram
v0
v4 v2 Energy E1 v0 v4 v2 Low
*Energy level transition
E1 v0
r3 r1
v4 v2
r3 r1
E0 v0
En: be subdivided into a number of Vn(Vibraional sublevels) Vn: be subdivided into a number of rn (rotational sublevels)
350~750 T: 2400-3000K I ∝ V4
Designed by Amy. L
1. light source: 200-750nm Over the entire wavelength range of interest: continuous, high intensity , stable and long life *Hydrogen/deuterium lamp
Io= Ia + It
b: path length ( cm) c:concentration(<0.01mol/L) k: absorptivity; absorption capability for a particular substance When a beam of parallel monochromatic light pass through a cell of solution, A is proportion to the production of b and c.
back
120nm-60μm
1 cm 0.5cm 2 cm 3 cm
Littrow prism x nm-xxxμm
dispersion
>100 grooves/mm 4000 grooves/mm
Materials: *glass: can be used down to about 320nm, or will absorb most of the radiation. *quartz: can be used under or above 320nm, more expensive.
Designed by Amy. L
II. Lambert - Beer law
A = -lgT=lg I0 / It = kbc
I0 c b It
path length 路径长度 concentration 浓度 absorptivity 吸光系数 characteristic value 特征值 monochromatic 单色的 transparent 透明的 production 乘积
c = 3*108m.s-1 h = 6.63*10-34J.s-1 1nm=10-9m
wavelength 波长 frequency 频率 Plank constant 普郎克常数 nanometer 纳米
UV： 200-400nm VIS： 400-750nm
Designed by Amy. L
λ(nm) λ(nm) often used
2. Monochromator: slit
collimation
monochromator 单色器 slit 狭缝 collimation 准直, 校正平行 ispersion 色散元件 focus 聚焦 concave mirror 凹面镜
Designed by Amy. L
2. Monochromator: slit
collimation
3. Absorption cell:
prism 棱镜 refraction 折射 grating 光栅 groove 刻槽 interference 干涉 diffraction 衍射 holograph 全息照相
Designed by Amy. L
2. Absorption curve/spectrum
A
λmax
Na : 1s22s22p63s1
+
Ions have inert gas structure ( an even number of electrons), each electron paired with one of opposite spin direction. CuCl2 : blue/green
continuous, high intensity , stable and long life *Tungsten filament lamp
λ(nm) ( )
tungsten 钨 filament 灯丝
λ( (nm) ) often used
deuterium
氘
350~2000
light source mono chromator absorption cell detector indicator
I. Transmittance (T)& Absorbance(A)
T = It / I0 A=-lgT=lg I0 / It 0% ~ 100%
0 ~ ∞
Designed Designed by Amy. by Amy. L L
2
III. Key Point
A=-lgT=lg I0 / It A = k (ε, a ) bc Notice: c (mol.L-1) k: ε (L.mol-1.cm-1) c (g.L-1) k: a (L.g-1.cm-1)
identify 鉴别 qualitative 定性的 quantitative 定量的 absorption 吸收 radiation 辐射 molecule 分子
Designed by Amy. L
Designed by Amy. L
II. Terms:
beam 光束 emission photon 光子 sample sample emission reflection 发射 refraction reflection th process of the f a photon h t b being i emitted itt d 反射 scattering by solid impurity particles refraction 折射 absorption 吸收 radiation sample 辐射 absorption transmission along radiation beam, intensity transmission 透射
(525nm)
manganese(Mn )ε 0.02 (525nm)
k stands for the sensitivity. permanganateL(MnO -) ε 2×103 4
§4. UV-VIS Spectrophotometer I. Major component
Types
1. light source: 200-750nm Over the entire wavelength range of interest:
E0
Electronic transition
Vibrational transition
Rotational transition
v0
*Conclusion:
Absorption of light is due to the transition of electrons from low to high energy levels Inorganic substances: presence of unpaired electrons NaCl : colorless
UV-VIS SPECTROPHOTOMETRY
ultraviolet 紫外的 visible 可见的 p spectrophotometry 分光光度法
§1. Introduction
I. UV-VIS spectrophotometry:
A kind of analytical method to identify chemical species (qualitative analyses) and determine the amount of a particular species (quantitative analyses). This method is based on measuring the absorption of UV or visible radiation by molecules. molecules