Exploitation of second-order effects in atomic force microscopy

Patent metadata

Field	Value
Publication number	US-9541575-B2
Application number	US-201414554394-A
Country	US
Kind code	B2
Filing date	Nov 26, 2014
Priority date	Nov 26, 2014
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A processing system cooperates with an atomic force microscope operating in ramp mode at a ramp frequency is configured to collect data indicative of at least one of physical and chemical properties of a sample. The system collects data indicative of probe movement at a frequency that is higher than the ramp frequency. This data comprises a second-order portion of the probe's signal. Based at least in part on the second-order portion, the processor obtains a parameter that is indicative at least one of a physical and a chemical property of a sample.

First claim

Having described the invention and a preferred embodiment thereof, what is claimed as new and secured by Letters Patent is:

1. An apparatus for evaluating one of a physical and a chemical property of a surface, said apparatus comprising a processing system configured to cooperate with an atomic force microscope operating in a nonresonant ramp mode at a ramp frequency, said processing system being configured to collect a data indicative of at least one of the physical and the chemical properties of a sample, wherein said processing system is configured to receive a probe signal indicative of a movement of a probe at a frequency that is higher than said ramp frequency;
wherein said probe signal comprises a contact portion and a rebound portion, and wherein said probe signal comprises a first portion indicative of a cantilever deflection of said atomic force microscope and a second portion that consists of second-order effects of motion of said cantilever;
and wherein said processing system is further configured to obtain through processing a parameter that is indicative at least one of the physical and the chemical property of the sample based at least in part on said second portion of said probe signal;
wherein the second order effects of either contact or rebound portions of the probe signal are processed to provide information about said parameter.

2. The apparatus of claim 1 , wherein said processing system is configured to obtain a restored adhesion.

3. The apparatus of claim 1 , wherein said processing system is configured to obtain an average restored adhesion.

4. The apparatus of claim 1 , wherein said processing system is configured to obtain a viscoelastic adhesion response.

5. The apparatus of claim 1 , wherein said processing system is configured to receive the probe signal having a noise portion that comprises a noise in said contact portion of said probe signal, and a scanner signal that controls ramping motion of said probe;
wherein said a noise further comprises the second-order effects.

6. The apparatus of claim 5 , wherein said processing system is configured to obtain a restored adhesion height.

7. The apparatus of claim 5 , wherein said processing system is configured to obtain a zero deflection height.

8. The apparatus of claim 7 , wherein said zero deflection height is determined based on a retraction curve.

9. The apparatus of claim 7 , wherein said zero deflection height is determined based on an approach curve.

10. The apparatus of claim 5 , wherein said processing system is configured to obtain a viscoplastic height shift.

11. The apparatus of claim 1 , wherein said processing system is configured to receive and process the probe signal in which said second portion comprises a periodic oscillation superimposed on said contact portion of said probe signal during contact of said probe with said sample.

12. The apparatus of claim 11 , wherein said processing system is configured to obtain a parameter indicative of a slip-stick motion.

13. The apparatus of claim 12 , wherein said processing system is configured to obtain the parameter indicative of slip-stick motion based on oscillation superimposed on an approaching portion of said contact portion.

14. The apparatus of claim 12 , wherein said processing system is configured to obtain the parameter indicative of slip-stick motion based on oscillation superimposed on a retracting portion of said contact portion.

15. Apparatus of claim 1 wherein said processing system is configured to receive a probe signal, wherein said processing system is further configured to receive a scanner signal that controls ramping motion said probe.

16. The apparatus of claim 15 , wherein said processing system is configured to obtain a parameter indicative of dynamic creep phase shift.

17. The apparatus of claim 1 wherein said processing system is configured for an offline processing.

18. The apparatus of claim 1 , wherein said processing system is configured for a real-time processing.

19. The apparatus of claim 1 , wherein said processing system comprises a floating-point gate array for a real-time processing.

20. The apparatus of claim 1 , further comprising an atomic force microscope coupled to said processing system, wherein said processing system is configured to receive said probe signal from said atomic three microscope.

Assignees

• Univ Tufts

Inventors

• Dokukin Maxim
• Sokolov Igor

Classifications

• G01Q60/32

  AC mode · CPC title

• G01Q30/04 Primary

  Display or data processing devices · CPC title

• G01Q60/28

  Adhesion force microscopy · CPC title