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Title:Electronic Transition Spectra Of Thiophenoxy And Phenoxy Radicals In Hollow Cathode Discharges
Author(s):Araki, Mitsunori
Contributor(s):Tsukiyama, Koichi; Niwayama, Kei; Wako, Hiromichi
Abstract:Diffuse interstellar bands (DIBs) still remain the longest standing unsolved problem in spectroscopy and astrochemistry, although several hundreds of DIBs have been already detected. It is expected that identifications of DIBs can give us crucial information for extraterrestrial organic molecule. One of the best approaches to identify carrier molecules of DIBs is a measurement of DIB candidate molecule produced in the laboratory to compare their absorption spectra with astronomically observed DIB spectra.\\ Radical in a gas phase is a potential DIB candidate molecule. The electronic transitions of polyaromatic hydrocarbon radicals result in optical absorption. However, because radicals are unstable, their electronic transitions are difficult to observe using a laboratory spectrometer system. To solve this difficulty, we have developed a glow-discharge cell using a hollow cathode in which radicals can be effectively produced as a high-density plasma. The radicals produced were measured by using the cavity ringdown (CRD) spectrometer and the discharge emission spectrometer.\\ The CRD spectrometer, which consists of a tunable pulse laser system, an optical cavity and a discharge device, is an apparatus to observe an high-resolution optical absorption spectrum. The electronic transition of the thiophenoxy radical C$_{6}$H$_{5}$OS was observed in the discharge emission of thiophenol C$_{6}$H$_{5}$OH. The electronic transition frequency of the thiophenoxy radical was measured.\\ A optical discharge emission was examined by using a HORIBA Jobin Yvon iHR320 monochromator. We detected the phenoxy radical C$_{6}$H$_{5}$O in the discharge of phenol C$_{6}$H$_{5}$OH. The band observed at 6107 \AA in the discharge was assigned to the electronic transition of the phenoxy radical on the basis of the sample gas dependences and the reported low resolution spectrum.\footnote{B. Ward, Spectrochimica Acta, 24A, 813, 1968} The electronic transition frequency of the phenoxy radical was measured.\\ Comparison studies of the thiophenoxy and phenoxy radicals were made with known DIB spectra.
Issue Date:2014-06-16
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:Araki, M.; Tsukiyama, K.; Niwayama, K.; Wako, H. ELECTRONIC TRANSITION SPECTRA OF THIOPHENOXY AND PHENOXY RADICALS IN HOLLOW CATHODE DISCHARGES. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.MF14
Rights Information:Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License.
Date Available in IDEALS:2014-09-17

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