AN INVESTIGATION OF THE ORIGINS AND EFFICIENCIES OF HIGHER-ORDER NONLINEAR SPECTROSCOPIC PROCESSES

We propose extending the site selection and mode selective capabilitie s of four-wave mixing spectroscopies to room-temperature samples using six-wave mixing to develop multiple Raman resonances. Calculations pr edict a coherent higher-order Raman excitation spectroscopy (CHORES) s hould be observable at excitation intensities > 1 GW/cm2, but there is also competition from a sequential CARS (SCARS) process. The SCARS me chanism dominates over CHORES for electronically non-resonant excitati ons. Since SCARS and CHORES have identical dependencies on both input intensities and resonances, phase-matching considerations must be used to spatially separate their respective contributions.