Determination of damping force between atomic force microscope tips and sample using an inverse methodology

In this Letter, the determination of the damping force between the atomic force microscope (AFM) tips and sample is regarded as an inverse vibration problem. The inverse solution methodology based on the conjugate gradient method is presented for estimating the interaction force and the damping force. The method is required to treat the inverse problem using available displacement measurements of AFM cantilever. Numerical results show that the method can accurately estimate the interaction force and the damping force even for problems with error of displacement measurement. In addition, the initial guesses for the interaction force can be arbitrarily chosen and the computing time required for the inverse calculations takes less than one second using a Pentium III-450 MHz PC.