Observation and Analysis of the Infrared Spectra of O2-HF near 3950 cm-1 and O2-DF Near 2900 cm-1
W M. Fawzy, C M. Lovejoy, David Nesbitt, Jon T. Hougen
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.
Journal of Chemical Physics
H-F stretch, infrared spectrum, open-shell complex, spin-rotation Hamiltonian, triplet oxygen, van der Waals complex, vibration-rotation spectral fit
, Lovejoy, C.
, Nesbitt, D.
and Hougen, J.
Observation and Analysis of the Infrared Spectra of O<sub>2</sub>-HF near 3950 cm<sup>-1</sup> and O<sub>2</sub>-DF Near 2900 cm<sup>-1</sup>, Journal of Chemical Physics
(Accessed December 7, 2023)