Topometrix AFM procedure

Procedure for use of Topometrix Explorer AFM1. Turn on both computer and TV monitors.2. Gently flip over AFM head and let it rest on holding pedestal.3. Mount half-moon shaped tip onto magnetic holder. Make sure tip is securely seated withfirm contact to back of magnetic holder and reasonably aligned.4. Mount sample puck onto magnetic base.5. Rotate both probe height screws in a clockwise direction one-half rotation to ensurecantilever is higher than sample surface.6. Gently grasp front sides of AFM head and flip over while securing holding with thepedestal.7. Place left rear screw mount in its proper resting groove followed by right rear screwmount into its proper resting groove and slowly begin dropping down AFM head until the front screw mount comes into contact with its proper resting groove. Keep watch on the TV monitor while doing this to ensure cantilever does not crash down onto sample.8. Double Click on SPM lab icon to open software program.9. Click on Image Acquisition icon (Cantilever image) located on top right of Tool bar.10. Click Ok once inside the Scanner Selection menu.11. Click Engage to apply voltage to the AFM head.12. Turn laser ON using High intensity setting.13. Slowly lower cantilever tip using the lower tip icon until the tip is just above samplesurface but not touching. Be aware of the tip shadow as a reference as to how high above the sample the tip is.14. Enter the T-B mode. Adjust the mirror using the Mirror adjustment knob(the longerknob on the left side of AFM head) until the signal is approximately 0nA. Continueadjusting mirror until signal trace crosses the 0nA level in both positive and negativeregions before setting the signal at 0nA.15. Enter the L-R mode. Adjust the photodiode using the Photodetector alignment knob(the shorter knob on the left side of AFM head) until the signal is approximately 0nA.Continue adjusting mirror until signal trace crosses the 0nA level in both positive andnegative regions before setting the signal.16. The laser signal should now be centered on the photodiode quadrants.17. Enter the Sum mode. Carefully make fine adjustments to the laser alignment screws(one at a time) to maximize the laser signal. For quality images, laser signal should be >11nA.18. Repeat steps 13 and 14 to re-center the laser signal. Check Sum signal again to ensuresignal is maximized.19. Set the initial scan parameters in the Acquisition Control Panel.These should be:Setpoint: 0.0nAScan Range: 20.00 um (can be adjusted later depending on sample size)Scan Rate: 20um/sResolution: 300Proportional gain: 1.0Integral gain: 0.520. Enter T-B mode. Decrease signal trace to approximately 50nA.21. Click the Tip Approach button. This will engage the 5-10 second computer automatedtip approach to the sample surface. Observe the signal trace increasing as the tip moves close to sample surface. At roughly the setpoint (0nA), the signal trace should display a momentary spike. This is an indication of the tip penetrating the water vapor layer on the sample surface and a good reference that the tip is in contact with sample.22. Verify the system is indeed in feedback mode by clicking on the Sensor Responsebutton. A positive sloping Deflection vs. Distance curve should be displayed with data points approximately lining up with the linear plot line.23. If system fails to reproduce the positive slope, a False Feedback error message willappear. Click on the Raise Tip button (once) to get out of feedback. In T-B mode try decreasing signal current more negative. Repeat steps 21-23.24. Initiate Line Scan to ensure that the probe tip is performing a level scan with the tipparallel to the sample surface. The slope (∆Z) of line scan should be approximately100-200nm/100µm. If this value is larger, adjust the left and right heightadjustment knobs until the proper ∆Z is achieved. For further instructions, referto “leveling procedure” sign posted on the side of computer monitor.25. The AFM is now ready to begin image acquisition. Click on the Instant Scan button tobegin scanning.26. During image acquisition, adjust scan mode and feedback parameters to achieve anoptimal image. Remember to restart the scan after changes have been made.27. After experiments are finished, turn off both monitors.28. Sign out logbook.Additional Procedure for Tapping Mode Operation1. Use same procedure as above for sample mounting and laser alignment.2. Before beginning cantilever tip tuning procedure be sure to enter the T-B Mode.3. Select Setup-> Non-Contact.4. Once the Non-Contact control window is loaded, select the Active box.5. Make sure the Amplitude button in the mode section is selected.6. Set the tune parameters to proper values which correspond to the installed Z scanner:Range: 0-600 HzDrive Amplitude: .2V (Note: Do not exceed .5V)Drive Frequency: To be determined by the cantilever resonance peakInput Gain: 27. Click the Spectrum button. At this time the system will sweep across the givenfrequency range and will then display the cantilever resonance peak.8. Click the left mouse button onto the narrow peak. This will be the cantilever resonancepeak. Then click the right mouse button to set the drive frequency, which will be used, for imaging.9. Adjust the Drive Amplitude value so that the free-oscillation amplitude (displayed onthe oscilloscope’s Internal Feedback signal of the T-B mode) is between –30 and –50nA.10. Adjust the Set Point value to be 50%.11. Drop tip down until cantilever tip is just above sample surface. Make sure the T-B modeis selected and begin Tip Approach sequence. This will bring tip into feedback mode at 50% of registered amplitude. Do Not Use the Sensor Response function while using the microscope in Non-Contact Mode.12. Initiate the Line Scan button to make sure the slope (∆Z) of line scan is approximately100-200nm/100µm. If it is larger, adjust the left and right height adjustment knobs until the proper ∆Z is achieved. For further instructions see the leveling procedure. 13. Proceed with normal operations for obtaining images.。