THEORETICAL-ANALYSIS OF LIGHT-INDUCTIVE FORCES IN SCANNING PROBE MICROSCOPY

When two objects of subwavelength size interact in the presence of a l ight beam, a spatially confined electromagnetic field arises in a smal l spatial region located at the immediate proximity of the particles. In scanning probe microscopy, such induced short-range interactions ch ange the magnitude of the forces interacting between the probe tip and the substrate. Depending on the frequency of light excitation with re spect to those of the gap modes associated with the tip-sample junctio n, these inductive forces act to pull the probe toward the surface. Su ch an effect can be used to record optical adsorption of various sampl es with an atomic-force microscope. In this paper we show that the acc urate description of the physical processes responsible for these forc es can be analyzed within the framework of the localized field-suscept ibility method. Practical solutions for the light-inductive force were found by discretization of the probe apex in real space. All multiple interactions including reflections with a substrate of arbitrary prof ile were accounted for by self-consistent procedures. We can therefore present simulations performed on systems of experimental interest.