Shear force/reflection near-field scanning optical microscopy

Abstract

The spatial resolution afforded by near-field scanning optical microscopy (NSOM) is primarily a function of tip size and tip-sample separation. Combining scanning force microscopy with NSOM allows one to maintain a small tip-sample separation distance and, consequently, optimize NSOM resolution. This provides, simultaneously, a topographic perspective of the sample as well as an NSOM image. We present, in this paper, an instrument that provides simultaneous shear force and reflection NSOM images. We also incorporate a tip deflection detection scheme that allows the force signal to be completely decoupled from the optical signal. In order to accurately analyze the NSOM images, it is important to understand the feedback mechanism so that proper image deconvolution can be performed. Considerations concerning the forces measured are made. A discussion concerning Raman scattering capabilities in this regime is also provided, along with some preliminary Raman data.