Rotational relaxation measurements on OCS using a beam maser

Casleton, Kent H.; Chien, Kuei-Ru; Foreman, P.B.; Kukolich, Stephen G.

doi:10.1016/0009-2614(75)80243-0

Cited by 6 publications

(1 citation statement)

References 14 publications

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“…OCS is a favorable molecule for microwave and millimeter wave experiments as it has quite intense transitions, and He will be the buffer gas used in future CPUF experiments. The pressure broadening coefficients for the OCS + He system have been studied for many years, usually using microwave spectroscopy [19][20][21][22][23][24] but also with infrared spectroscopy [25]. Theoretical pressure broadening crosssections have been calculated using a semiclassical relaxation theory [26] and the infinite order sudden approximation from a potential energy surface of OCS + He [27], the latter of which was compared against experimental data and found to disagree quite dramatically [21,25].…”

Section: Introductionmentioning

confidence: 99%

Design and performance of an E-band chirped pulse spectrometer for kinetics applications: OCS – He pressure broadening

Hays

Guillaume

Hearne

et al. 2020

Journal of Quantitative Spectroscopy and Radiative Transfer

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Product channel-specific reaction kinetics at low temperature presents a significant challenge for both experiment and theory but provides essential inputs for astrochemical models o f cold interstellar environments. Reaction kinetics studies using chirped pulse Fourier transform microwave (CP-FTMW) spectroscopy provide a potential solution but require the use of a buffer gas to thermalize the reactants and products; however, collisions with the buffer gas reduce the length of the detected signal, the free induction decay, through pressure broadening. The effect of this on time domain signals is largely unexplored using CP-FTMW spectrometers. A new E-band (60-90 GHz) spectrometer has been constructed using previously unavailable equipment in order to maximize its performance for detecting molecules in collisional environments. The design of this spectrometer is described in detail. The pressure broadening of OCS in He was used to test the spectrometer under collisional conditions similar to those that are routinely used to perform reaction kinetics measurements. The corresponding pressure broadening coefficients for transitions in this frequency range were determined at room temperature and the performance of the spectrometer was assessed in relation to recently reported chirped pulse in uniform flow experiments.

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