Je. Ivanecky et Jc. Wright, AN INVESTIGATION OF THE ORIGINS AND EFFICIENCIES OF HIGHER-ORDER NONLINEAR SPECTROSCOPIC PROCESSES, Chemical physics letters, 206(5-6), 1993, pp. 437-444
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.