SCANNING NEAR-FIELD OPTICAL MICROSCOPE DESIGNED FOR OPERATION IN LIQUIDS

We report on the construction of a scanning near-field optical microsc ope (SNOM), which has been designed to permit imaging at the solid/liq uid interface, The probe consists of a tapered fibre tip and the so ca lled lateral shear force is used for the tip-sample distance regulatio n, The liquid environment causes damping of the tip vibration and lowe ring of the resonance frequency by approx, 20% which can not be explai ned by the model of a harmonic oscillator, We demonstrate the optical and topographical resolution of the instrument utilizing test grids fo r atomic force microscopy, First results of in-situ observation of ads orption of human serum albumin proteins at a thin film of polystyrene from aqueous buffer solution are presented. (C) 1997 by John Wiley & S ons, Ltd.