Dynamics and Spectroscopies in Four-Wave Mixing with Coherent and Incoherent Light

Abstract

“Interferometric Coherent Raman Scattering” (ICRS) involving incoherent light is characterized by fringes (Rabi detuning oscillations (RDO’s)) or strongly down-converted Raman Bohr frequencies. New examples of RDO’s are shown involving both resonant and nonresonant components. Along the frequency axis the ICRS signal reveals new “zero linewidth” (ZLW) features that promise ultrahigh frequency resolved Raman spectroscopy. New examples of these features are shown. Neither RDO’s nor ZLW features are seen when using femtosecond light pulses. The latter, however, permit the resolution of stochastic line-shaping processes in real time. Thus a time resolved (25fs) CARS study of the ring breathing mode in liquid benzene has been completed. The line-shaping event is analyzed as a Kubo process. It is suggested that the spinning benzene ring may be principally responsible for the dephasing of this mode.