Abstract
Dynamic atomic force microscopy (DFM) is a powerful tool to observe various solid surfaces with high-spatial-resolution down to atomic scale in all environments (vacuum, air and liquid). Use of higher cantilever vibration modes is an effective method for reducing amplitude, which enhances the sensitivity of DFM. In this paper, we present an optically based DFM system combining photothermal excitation and laser Doppler velocimetry for utilizing the higher modes in liquid. By using the second flexural mode with the frequency of 1 MHz, we successfully reduced the tip amplitude down to 99 pm, and achieved atomic resolution DFM imaging of a cleaved mica surface in purified water. Cross sectional analysis of the images shows that individual atoms on the surface have small height differences up to 60 pm. [This abstract is not included in the PDF]
