Theory of Spectroscopy and Microscopy with Resonant Radiation Force

摘要

A scanning force microscopy is a powerful method to observe the microscopic properties and topography of nanostructures with high resolution [1,2], where the force ranging from 10{sup}(-9) to 10{sup}(-18) N between a probe tip and a sample is detected and utilized. In this field, the control of the external-field-induced force modulation is an important subject because it provides the information on the magnetic or electronic properties of the sample applied with magnetic or electric fields [3,4]. However, there are only few works related to the light-induced force in nano-systems because its mechanism has been unclear [5]. On the other hand, in the field of optical manipulation, it has been clarified that the sufficiently strong radiation force (RF) to handle nanoparticles is induced by light resonant with their electronic excited states [6]. The behavior of such a RF is sensitive to quantum properties of nano-objects depending on their size, shape and internal structure. In particular, in our recent work, we have revealed that the interparticle radiation force (IRF) arises between closely-spaced nano-objects by optical excitation of coupled states of polaritons (light-matter coupled states) in them [7]. The magnitude of IRF can be greater than that of RF for the small inter-object distance, and properties of IRF change reflecting coupling manners of polaritons in objects. Paying attention to these mechanisms, we explore the potential of spectroscopy and microscopy to observe quantum properties in nanoscale samples by detecting IRF.