Nonlinear-optical spectral interferometry of nanostructures using coherent anti-Stokes Raman scattering

The spectrum of coherent anti-Stokes Raman scattering (CARS) from Raman-active vibrations of gas-phase nitrogen molecules in a mesoporous silica aerogel host is experimentally studied. The CARS spectral profile under these conditions is a result of interference of the resonant part of nonlinear susceptibility, originating from nitrogen molecules in aerogel pores, and the nonresonant contribution, related to the mesoporous host. Raman-active modes of gas-phase molecular nitrogen give rise to intense resonances in the CARS spectrum, serving as reference spectral profiles for probing local parameters of a nanocomposite material (nanoCARS).