Investigation of the shape of the R(0) absorption line in ν3, N2O recorded from an axisymmetric supersonic free jet expansion

✍ Scribed by Keevin Didriche; Peter Macko; Michel Herman; Jonathan Thiévin; Abdessamad Benidar; Robert Georges

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 345 KB
• Volume: 105
• Category: Article
• ISSN: 0022-4073
• DOI: 10.1016/j.jqsrt.2006.10.002

✦ Synopsis

The hydrodynamic structure of an axisymmetric supersonic expansion can be regarded as a series of concentric divergent cones, with decreasing particle densities as the cone angle increases. Different groups of molecules therefore contribute to high-resolution absorption line shapes when optically probing the expansion in a direction perpendicular to the jet axis. These groups are distinguished by the cone angle, inducing a specific Doppler shift, and by the particle density, contributing a specific weight to the absorption intensity. As a result different broader line profiles are observed compared to room temperature spectra. This effect is investigated here selecting as the working example the R(0), n 3 absorption line in N 2 O recorded using a Fourier transform interferometer. Independent impact pressure and quadrupole mass spectrometric measurements are performed leading to two complementary maps of the expansion, allowing the recorded absorption line shape to be quantitatively modeled.