Acoustic damping rate measurements in binary mixtures of atomic species via transient-grating spectroscopy

The objective of this work is to investigate the ability of transient-grating spectroscopy (TGS) to measure accurately the acoustic damping rate by analyzing the temporal behavior of laser-induced gratings. Experiments are performed in a binary gaseous mixture, with a trace amount of NO2, as a function of both composition and pressure. Measured and theoretically calculated acoustic damping rates are compared using both a classical model and a more comprehensive model that included additional diffusive mechanisms. The TGS technique demonstrated here provides a nearly instantaneous measurement with reasonably high spatial resolution. The experimental data agree well with theoretical predictions.