Calibration of higher eigenmode spring constants of atomic force microscope cantilevers

Abstract

Standard spring constant calibration methods are compared when applied to highereigenmodes of cantilevers used in dynamic atomic force microscopy (dAFM). Analysis showsthat Sader’s original method (Sader et al 1999 Rev. Sci. Instrum. 70 3967–9), which relieson a priori knowledge of the eigenmode shape, is poorly suited for the calibration of highereigenmodes. On the other hand, the thermal noise method (Hutter and Bechhoefer 1993Rev. Sci. Instrum. 64 1868–73) does not require knowledge of the eigenmode and remainsvalid for higher eigenmodes of the dAFM probe. Experimental measurements of thermalvibrations in air for three representative cantilevers are provided to support the theoreticalresults.