Folded BOXCARS for rotational Raman studies (crossed-beam phase matching)

Nonplanar, crossed-beam phase matching has been employed to obtain pure rotational coherent anti-Stokes Raman spectroscopy (CARS) (and coherent Stokes Raman spectroscopy (CSRS)) spectra to within a few wavenumbers of the incident pump frequency. Using this approach, the rotational CARS (and CSRS) radiation is spatially separated from the pump and Stokes beams; therefore small Raman shifts can be observed with a single monochromator.