Two-photon resonance effect as observed in the CARS and CSRS of anthracene single crystal

Abstract
CARS and CSRS spectra of single crystalline anthracene have been investigated in a frequency range of excitation where the effect of TPA resonance is expected. A remarkable resonance effect has been observed in the line shape of Raman signals as well as in the background level height, in the spectra with exclusively b-polarized radiations. The CSRS spectra have been conspicuous by the development of negative Raman peaks, indicating the predominant importance of TPA–Raman interference contribution. By tracing the background level height against Raman peak height, the TPA band profile has been described to have the maximum near 31 400 cm−1 and the bandwidth of about 1000 cm−1.