Resolved rotation-vibration non-equilibrium with rotational VIPA-CARS

Simultaneous rotational and vibrational temperatures are measured in an N2 plasma with rotational coherent anti -Stokes Raman scattering (CARS) resolved with a virtually imaged phased array (VIPA)-based spectrometer. A VIPA spectrally separates rotational transitions for each vibra-tional state, allowing vibrational populations to be directly measured. VIPA-CARS is shown to provide more accu-rate measurements of non-equilibrium temperatures than grating-resolved rotational CARS. The general character-istics, limitations, and potential uses of VIPA-CARS are discussed. (C) 2022 Optica Publishing Group