The measurement of hysteretic forces by dynamic AFM

The effect of hysteretic force–distance relationships on the measurement process of tip–sample interactions by dynamic atomic force microscopy (AFM) is examined. A hysteretic force obtained from the model by Muller, Yushenko and Derjaguin is used in combination with a computer simulation of the measurement process of frequency modulation AFM with constant amplitude. It is shown how hysteresis in the force curve and hysteretic damping forces influence not only the excitation amplitude but also the frequency shift. Thus, the division between the measurement of conservative forces via the frequency shift and dissipative forces via the excitation amplitude is broken up. Additional analytical calculations are used in order to explain the simulation data. The implications of realistic experimental situations are discussed.