Mapping mechanical properties on the nanoscale using atomic-force acoustic microscopy

An image of the normalized contact stiffness k*/k^sub c^ calculated from the images of f^sub 1^ and f^sub 2^, is shown in Figure 3c. The image was calculated from the contact-resonance-frequency images on a pixel-by-pixel basis with the AFAM point approach described. To calculate a map of the indentation modulus M from the contact-stiffness image, Hertzian contact mechanics were used and it was assumed that the mean value of k*/k^sub c^ for the SiO^sub 2^ region corresponded to M^sub SiO2^ = 75.1 GPa.