Time-resolved CO_(2) thermometry for pressures as great as 5 MPa by use of pure rotational coherent anti-Stokes Raman scattering

摘要

Pure rotational coherent anti-Stokes Raman scattering measurements of pure CO_(2) have been performed in a temperature range from 300 to 773 K and for pressure from 0.1 to 5 MPa for the purpose of time-resolved CO_(2) thermometry. Particular emphasis was put on the comparison of several linewidth approximations to model the experimental spectra. Generally good agreement of the temperature mean values with the thermocouple reference has been found for all models over almost the whole pressure and temperature range investigated. The standard deviations, which increased with temperature, were comparable with or better than the results gained for single-shot measurements of pure N_(2) or O_(2)-N_(2) mixtures. Yet for high particle densities close to the critical point of CO_(2) the limitation of the models became obvious, owing to the strongly increased influence of motional narrowing effects. The characteristics of these effects have been demonstrated by measurements even closer to the critical conditions.