Temperature dependent determination of the S-branch Raman linewidths of oxygen and carbon dioxide in an oxyfuel relevant mixture

The temperature dependence of the O-2 and CO2 S-branch linewidths in a 30/70% O-2 - CO2 mixture between 295 K and 1900 K has been studied by a picosecond time-resolved pure rotational coherent anti-Stokes Raman scattering (RCARS) approach. The S-branch Raman linewidths are required for diagnostics of thermodynamic properties in oxyfuel combustion processes by RCARS, where this mixture is of special interest, because it is regularly used to replace air when transiting from air-fed to oxyfuel combustion. The obtained linewidths for oxygen and carbon dioxide show a strong deviation from pure self-broadened linewidths and previously used Q-branch linewidths, respectively. A discussion on the expected impact on RCARS thermometry and concentration evaluations as well as a description of specific properties of oxygen and carbon dioxide and their effect on the dephasing behavior of the Raman coherences and, thereby the Raman linewidths, is included, along tabulated linewidths data of both molecules. (C) 2021 Optical Society of America

Automated summary

This paper investigates the temperature dependence of the O-2 and CO2 S-branch linewidths in a 30/70% O-2 - CO2 mixture using a picosecond time-resolved pure rotational coherent anti-Stokes Raman scattering (RCARS) approach. The obtained linewidths show significant deviations from pure self-broadened linewidths and previously used Q-branch linewidths. Discussions are also provided on the implications for RCARS thermometry and concentration evaluations.