The Effect Of Humidity On Atomic Force Microscope Imaging

Atomic Force Microscope (AFM) is a tool that uses the interaction between probe tip and sample surface to obtain morphology. In recent years, artifacts should be excited attention. Impurities, humidity, temperature, the instrument itself may have an impact on imaging accuracy. The domestic and overseas results show that influence of humidity on imaging is significant. The liquid bridge forms in humid environment, this paper focus on researching the factor called humidity. By thermodynamic analysis combined with experiment we obtain three important parameters:Energy dissipation of cantilever, tip-sample distance and the maximum adhesion force. These three parameters can be used to measure the effect degree. The main contents of this paper are: Thermodynamic analysis of liquid bridge; calculation with C++language; Finite element modeling and analysis of probe tip; Force-Displacement curve measurement in different humidity.It has been seen that the theoretical value and experimental data of dissipation energy are consistent. Thermodynamic method is applied to study the interaction between tip and surface which has been approved by experiments. Through theory analysis and experiment we can obtain:the dissipation energy of cantilever increases significantly at high humidity; the amplitude change of cantilever increases with dissipation energy increasing; the phase of cantilever increases with dissipation energy increasing and it is a linear variation. We combine theoretical value with experimental data to analyze the vibration of cantilever and obtain a qualitative conclusion that the dissipation energy can change the amplitude and phase of cantilever.