CARS spectra of polystyrene sheet at excitation of fs pulses and chirped pulses

Abstract

Two-beam coherent anti-Stokes Raman scattering (CARS) spectroscopy setup is built. Measurements of CARS spectra generated from polystyrene (PS) sheet under excitation of femtosecond (fs) pulses and chirped pulses are demonstrated. The pump-Stokes time delay is adjusted at fixed step of 6 fs and transient CARS spectra is measured at every pump-Stokes time delay. Two-dimensional plots depicting intensity of fs CARS, chirped Stokes CARS, chirped pump/probe CARS and spectral focusing CARS as a function of the wavenumber and the pump-Stokes time delay are realized. Excitation situation of Raman resonances in fingerprint region of polystyrene molecule is discussed in conditions of un-chirped and chirped CARS spectra. Capacity of chirped Stokes CARS, chirped pump/probe CARS and spectral focusing CARS in improving spectral resolution over fs CARS is systematically analyzed.