Coherent anti-Stokes Raman scattering on single-walled carbon nanotube thin films excited through surface plasmons

Abstract

We report experimental data that indicate an anti-Stokes Raman emission, reminiscent of coherent anti-Stokes raman scattering. It originates from a wave mixing process between the incident laser light $({\ensuremath{\omega}}_{l})$ and Stokes Raman light $({\ensuremath{\omega}}_{s})$ generated by a surface enhanced Raman scattering (SERS) mechanism. The variation of anti-Stokes SERS spectra of single-walled carbon nanotubes, copper phthalocyanine, and poly(bithiophene) as a function of the film thickness, the laser excitation intensity, and the numerical aperture of the microscopic objective used for collecting the scattered light demonstrate the described phenomenon.