THF FORMATION MECHANISMS OF $D_{3}$: AN INFRARED SPECTROSCOPIC INVESTIGATION
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Date
2000
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Ohio State University
Abstract
In 1993, we reported observations of the infrared absorption spectra of $D_{3}$ with a difference frequency laser system in the frequency ranges around $3600 cm^{-1} (3s^{2} A^{\prime}_{1}\leftarrow 3p^{2} E^{\prime})$ and $3900 cm^{-1} (3d \leftarrow 3p^{2} E^{\prime})^{a}$. The observed line shapes exhibited a board non-Maxwellian velocity distribution, and the line shapes depended on the rotational states. At that time, the line shapes and the widths were not completely understood. Here we present a more detailed and consistent analysis. Most lines of the $3600 cm^{-1}$ band appear to be a superposition of two components, broader and narrower features, for some transitions with an opposite phase. From a broader flat-topped line profile, it is concluded that $D_{3}$ carries excess translational energy of 0.4 eV and is formed through the dissociative recombination reaction of $D^{+}_{5}$ with electrons. The rotational dependence of the line shapes of the $3600 cm^{-1}$ band is brought about by a competition between the predissociation in the $3s^{2} A^{\prime}_{1}$ state and the radiative decay in the $3p^{2} E^{\prime}$ state. The shorter lifetimes of the 3d complex make the line shape of the $3900 cm^{-1}$ band simpler, a superposition of two absorption profiles with different widths. It is found that the widths of the lines of the $3900 cm^{-1}$ band are larger than those for the $3600 cm^{-1}$ band lines. The greater widths of the $3900 cm^{-1}$ band are attributed to unresolved spin-splittings. Attempts to observe similar absorption lines of $H_{3}$ were unsuccessful, presumably due to much shorter lifetimes.
Description
$^{a}$T. Amano and Man-Chor Chan, paper TD02, 48th International Symposium on Molecular Spectroscopy, Columbus, Ohio, 1993
Author Institution: Institute for Astrophysics and Planetary Sciences, Ibaraki University; Department of Chemistry, The Chinese University of Hong Kong
Author Institution: Institute for Astrophysics and Planetary Sciences, Ibaraki University; Department of Chemistry, The Chinese University of Hong Kong