How the alternating degeneracy in rotational Raman spectra of CO2 and C2H2 reveals the vibrational temperature

TitleHow the alternating degeneracy in rotational Raman spectra of CO2 and C2H2 reveals the vibrational temperature
Publication TypeJournal Article
Year of Publication2018
AuthorsD.CM van den Bekerom, J.M Palomares-Linares, E.M van Veldhuizen, S. Nijdam, M.CM van de Sanden, G.J van Rooij
JournalApplied Optics
Volume57
Issue20
Pagination5694-5702
Date PublishedJul
Abstract

The contribution of higher vibrational levels to the rotational spectrum of linear polyatomic molecules with a center of symmetry (CO2 and C2H2) is assessed. An apparent nuclear degeneracy is analytically formulated by vibrational averaging and compared to numerical averaging over vibrational levels. It enables inferring the vibrational temperature of the bending and asymmetric stretching modes from the ratio of even to odd peaks in the rotational Raman spectrum. The contribution from higher vibrational levels is already observable at room temperature as g e/o=0.96/0.04 for CO2 and g e/o=1.16/2.84 for C2H2. The use of the apparent degeneracy to account for higher vibrational levels is demonstrated on spectra measured for a CO2 microwave plasma in the temperature range of 300-3500 K, and shown to be valid up to 1500 K.

DOI10.1364/AO.57.005694
Division

MaSF

Department

NFC

PID69ff8181930db4c659c3f25374415dfd
Alternate TitleAppl. Opt.
LabelOA
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