Knowledge Bank

This work has demonstrated and interpreted the observation of resonance fluorescence generated in a three photon process similar to that observed for coherent anti-Stoker Raman scattering (CARS). Using an experimental setup similar to those developed for CARS, we have resonantly excited $NO2$ in several regions of its-visible absorption. The anti-Stokes emission was incorrectly interpreted by conventional CARS/Raman theory. Only when this emission war considered to be fluorescence could the observed spectra be analyzed. The process and criteria used to come to this conclusion will be discussed. CAFE spectra of $NO2$ have been measured, analyzed, and used to resolve electronic and vibrational contributions to the absorption process in $NO2$. These and other applications of CAFE will be discussed.