The authors analyze photothermal excitation of a single-crystalline silicon cantilever for higher vibration modes in liquid. The cantilever is bent by thermal stress generated by thermal diffusion in the direction perpendicular to the cantilever surface. Because the cantilever is made of a homogeneous material, thermal diffusion in the longitudinal direction does not generate thermal stress. Therefore, the higher vibration modes having small spatially periodic mode shapes are easily and effectively excited. The authors compared the excitation efficiency of two optical wavelengths, 405 and 780 nm. The 405 nm laser-diode beam was found to be 2.3-4.2 times more effective in exciting the second flexural mode compared with the 780 nm beam. These differences in excitation efficiency are attributed to the absorbance characteristics of silicon and were confirmed by measuring the transmitted light power (lost power) against the incident light power. Vibration amplitude of each mode was sufficient to operate dynamic-mode atomic force microscopy in liquid. (C) 2009 American Vacuum Society [DOI: 10.1116/1.3077487]