Thermal noise in contact atomic force microscopy

2021 ◽  
Vol 129 (23) ◽  
pp. 234303
Author(s):  
Chengfu Ma ◽  
Chenggang Zhou ◽  
Jinlan Peng ◽  
Yuhang Chen ◽  
Walter Arnold ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Thermal Noise ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

2013 ◽  
Vol 4 ◽  
pp. 32-44 ◽  
Author(s):  
Jannis Lübbe ◽  
Matthias Temmen ◽  
Sebastian Rode ◽  
Philipp Rahe ◽  
Angelika Kühnle ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Signal Processing ◽  
Transfer Function ◽  
Spectral Density ◽  
Thermal Noise ◽  
Noise Spectral Density ◽  
Force Microscopy ◽  
Atomic Force ◽  
Noise Limit ◽  
Signal Processing Electronics

The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM) consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density d z at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density d Δ f at the demodulator output in dependence of cantilever properties and settings of the signal processing electronics in the limit of a negligible tip–surface interaction and a measurement under ultrahigh-vacuum conditions. For a quantification of the noise figures, we calibrate the cantilever displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured d z , we predict d Δ f for specific filter settings, a given level of detection-system noise spectral density d z ds and the cantilever-thermal-noise spectral density d z th. We find an excellent agreement between the calculated and measured values for d Δ f . Furthermore, we demonstrate that thermal noise in d Δ f , defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A system with a low-noise signal detection and a suitable cantilever, operated with appropriate filter and feedback-loop settings allows room temperature NC-AFM measurements at a low thermal-noise limit with a significant bandwidth.

scholarly journals Self Heating of an Atomic Force Microscope

10.14311/1141 ◽  
2010 ◽  
Vol 50 (1) ◽  
Author(s):  
O. Kučera
Keyword(s):  
Atomic Force Microscopy ◽  
Atomic Force Microscope ◽  
Thermal Noise ◽  
External Noise ◽  
Force Microscopy ◽  
Self Heating ◽  
Atomic Force ◽  
Optical Lever ◽  
Many Sources ◽  
Vibrational Noise

Atomic force microscopy (AFM) is a sensitive technique susceptible to unwanted influences, such as thermal noise, vibrational noise, etc. Although, tools that protect AFM against external noise have been developed and are widely used, there are still many sources of inherent noise. One of them is self-heating of the apparatus. This paper deals with self-heating of the AFM using an optical lever. This phenomenon is shown to be substantial in particular after activation of the microscope. The influence on the intrinsic contact noise of AFM’s is also examined. 

scholarly journals Determining cantilever stiffness from thermal noise

2013 ◽  
Vol 4 ◽  
pp. 227-233 ◽  
Author(s):  
Jannis Lübbe ◽  
Matthias Temmen ◽  
Philipp Rahe ◽  
Angelika Kühnle ◽  
Michael Reichling
Keyword(s):  
Atomic Force Microscopy ◽  
Spectral Analysis ◽  
Thermal Noise ◽  
Oscillation Mode ◽  
Thermal Bath ◽  
Frequency Range ◽  
Force Microscopy ◽  
Experimental Systems ◽  
Atomic Force ◽  
Power Spectral

We critically discuss the extraction of intrinsic cantilever properties, namely eigenfrequency f n , quality factor Q n and specifically the stiffness k n of the nth cantilever oscillation mode from thermal noise by an analysis of the power spectral density of displacement fluctuations of the cantilever in contact with a thermal bath. The practical applicability of this approach is demonstrated for several cantilevers with eigenfrequencies ranging from 50 kHz to 2 MHz. As such an analysis requires a sophisticated spectral analysis, we introduce a new method to determine k n from a spectral analysis of the demodulated oscillation signal of the excited cantilever that can be performed in the frequency range of 10 Hz to 1 kHz regardless of the eigenfrequency of the cantilever. We demonstrate that the latter method is in particular useful for noncontact atomic force microscopy (NC-AFM) where the required simple instrumentation for spectral analysis is available in most experimental systems.

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