High resolution polarization spectroscopy and laser induced fluorescence of CO2 around 2μm

Abstract

High resolution Infrared Polarisation Spectroscopy (IRPS) and Infrared Laser Induced Fluorescence (IRLIF) techniques were used to probe CO2/N-2 binary gas mixture at atmospheric pressure and ambient temperature. The probed CO2 molecules were prepared by laser excitation to an overtone and combination ro-vibrational state (12(0)1, J = 15) of CO2, centred at 4988.6612 cm(-1). IRPS and IRLIF line profiles were recorded for several CO2/N-2 binary mixtures. The observed IRLIF line shapes have the expected Lorentzian form while the observed IRPS line shapes are narrower by a factor of two than those recorded with the IRLIF and appear to have a Lorentzian-cubed profile. The recorded line profiles provide measurements of the pressure-broadening coefficient directly at atmospheric pressure. The Full-Width-Half-Maxima (FWHM) pressure broadening coefficients are measured, based on IRLIF, to be 0.2174 0.0092 cm(-1) atm(-1) and 0.1327 +/- 0.0077 cm(-1) atm(-1) for self- and N-2 collision broadening, respectively. The broadening coefficients obtained based on IRPS were measured to be similar to 8% larger than those obtained with IRLIF. (Less)