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Title:SUB-DOPPLER INFRARED SPECTROSCOPY OF JET COOLED HCCL DIRADICAL: THE CH STRETCH AND VIBRATIONAL COUPLING IN THE GROUND ELECTRONIC STATE
Author(s):Scrape, Preston G.
Contributor(s):Nesbitt, David; Lesko, Daniel; Kortyna, Andrew
Subject(s):Radicals
Abstract:Diradical carbenes have long been recognized as important intermediates in a range of chemical processes, with the carbene's chemical reactivity being sensitive to the particular ground-state electronic structure. We have undertaken an investigation of chlorocarbene (HCCl) by seeding CHCl$_3$ into a Ne/He/H$_2$ mixture and passing this mixture through a pulsed slit discharge. In the discharge environment, the CHCl$_3$ undergoes a double Cl atom removal process through a combination of electron dissociative attachment and hydrogen abstraction. The subsequent jet expansion cools the HCCl diradical to a 32 K rotational temperature. With the goal of assisting the search for HCCl chemistry in interstellar molecular clouds, the rotational constants for the ground singlet state of both the $^{35}$Cl and $^{37}$Cl isotopologues are determined through least-squares fits of ground-state combination differences to an asymmetric top Watson Hamiltonian. A Watson Hamiltonian is also used to extract rotational constants for the nominally (100) vibrationally excited state, with a highly mixed combination band (nominally (012), one quantum of H-C-Cl bend plus two quanta of C-Cl stretch) of comparable intensity found within a few wavenumbers (cm$^{-1}$) of the CH stretch band origin. The proximity of these two bands and the comparable infrared intensities of both combination and fundamental bands points towards a highly mixed state with strong anharmonic coupling between these two zeroth order modes. We quantify the anharmonic coupling in a 2x2 matrix deperturbation treatment and find it to be similar in magnitude to the previously measured spin-orbit coupling constants between the singlet and nearby lying triplet manifold of states.
Issue Date:06/20/18
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:APS
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/100703
DOI:10.15278/isms.2018.WD01
Other Identifier(s):WD01
Date Available in IDEALS:2018-08-17
2018-12-12


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