Elucidating the spectral and temporal contributions from the resonant and nonresonant response to femtosecond coherent anti-Stokes Raman scattering.

A theoretical expression is developed for femtosecond coherent anti-Stokes Raman scattering (CARS) to quantitatively account for the vibrational line shape in the presence of nonresonant signal. The contributions of the resonant and nonresonant components are extracted from the emitted signal line shape as a function of Stokes wavelength and as a function of the temporal overlap of the two pump pulses (for spectrally resolved femtosecond CARS). The theory is compared to the measured spectra of the oxygen vibrational transition DeltaG(01)=1556.4 cm(-1) for temporal detunings of 0 and 700 fs.