Sub-doppler infrared spectroscopy of jet cooled HCCl diradical: The CH stretch and vibrational coupling in the ground electronic state

Scrape, Preston G.

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https://hdl.handle.net/2142/100703 Copy

Description

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

Issue Date

2018-06-20

Keyword(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 CHCl3 into a Ne/He/H2 mixture and passing this mixture through a pulsed slit discharge. In the discharge environment, the CHCl3 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 35Cl and 37Cl 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.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100703

DOI

10.15278/isms.2018.WD01

Copyright and License Information

Copyright 2018 Preston G. Scrape

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