Observation and Analysis of the Infrared Spectra of O2-HF near 3950 cm-1 and O2-DF Near 2900 cm-1

Published

July 1, 2002

Author(s)

W M. Fawzy, C M. Lovejoy, David Nesbitt, Jon T. Hougen

Abstract

Spectra were recorded in the H-F stretching region for both O2-HF and O2-DF, using a laser difference-frequency spectrometer coupled to a slit-nozzle expansion. By varying the ratio of oxygen to carrier gas, beam temperatures ranging from 5 to 16 K could be obtained. Relative measurement precision for unblended lines, i.e., precision for frequency intervals, is estimated to be 0.0001 cm-1. Each spectrum was visually subdivided into a stronger (cold) spectrum and a weaker (hot) spectrum. Lines in the cold spectrum were fit to nearly experimental error, using a rotational Hamiltonian for open-shell complexes taken from the literature. For O2-DF, 21 rotational and spin-rotational parameters (10 each for the upper and lower state plus the band origin) were used to fit 86 transitions to a standard deviation of 0.0002 cm-1. For O2-HF, 19 rotational and spin-rotational parameters were used to fit 83 transitions to a standard deviation of 0.0004 cm-1. The slightly poorer quality of the fit for O2-HF than for O2-DF is probably related to the somewhat larger vibrational amplitudes expected for the van der Waals motions in the protonated species. In spite of strenuous efforts a simultaneous global fit to measurement error of the five cold-spectrum branches and seven hot-spectrum branches together could not be achieved, suggesting some improvement in the model used to derive the fitting Hamiltonian may be necessary.

Citation

Journal of Chemical Physics

Volume

117

Issue

No. 2

Pub Type

Journals

Keywords

H-F stretch, infrared spectrum, open-shell complex, spin-rotation Hamiltonian, triplet oxygen, van der Waals complex, vibration-rotation spectral fit

Citation

Fawzy, W. , Lovejoy, C. , Nesbitt, D. and Hougen, J. (2002), Observation and Analysis of the Infrared Spectra of O₂-HF near 3950 cm^-1 and O₂-DF Near 2900 cm^-1, Journal of Chemical Physics (Accessed July 18, 2024)