Toward Gas-Phase Thermometry Using Pure-Rotational Impulsive Stimulated Raman Scattering Spectroscopy with a Low-Energy Femtosecond Oscillator

Femtosecond coherent Raman techniques have significant diagnostic value for the sensitive and non-intrusive measurement of temperature, pressure, and composition of gas mixtures. Due to the low density of samples, however, such measurements make use of high-energy amplified laser sources, with unwieldy and costly experimental setups. In this paper, we demonstrate an experimental setup equipped with a low-energy and low-average-power femtosecond oscillator allowing measurement of the pure-rotational spectrum of nitrogen down to atmospheric pressure using impulsive stimulated Raman scattering. Using a simplified model to analyze the experimental data we were able to derive the gas temperature with reasonable accuracy.