Hybrid femtosecond/picosecond pure rotational anti-Stokes Raman spectroscopy of nitrogen at high pressures (1-70 atm) and temperatures (300-1000 K)

Abstract

We demonstrate hybrid femtosecond/picosecond (fs/ps) pure-rotational coherent anti-Stokes Raman spectroscopy (RCARS) at high temperatures and pressures. Pulse-shaper-produced 40 fs pulses and bandwidth-narrowed, frequency-upconverted 5 ps pulses interact in a high-pressure cell containing N2 at 1-70 atm and 300-1000 K. Accurate experimental temperatures evaluated from fits to model rotational spectra confirm that the sensitivity and precision advantages of hybrid fs/ps RCARS can be exploited in characterizing combustion environments, even in the pressure regime where significant collisional energy transfer and line broadening cannot be neglected.