Title: Infrared spectroscopy of jet-cooled HCCl singlet chlorocarbene diradical: CH stretching and vibrational coupling dynamics

Abstract

Quantum shot noise limited laser absorption methods are used to obtain first high-resolution infrared rovibrational spectra of jet cooled chlorocarbene (HCCl) diradical in a supersonic slit-jet discharge expansion spectrometer. The rotationally resolved absorption spectra of the C–H stretch ν₁ fundamental are analyzed in the framework of a Watson non-rigid asymmetric rotor Hamiltonian model. Further analysis of the mid-infrared data reveals the additional presence of what has nominally been assigned as the $$\tilde x$$(012) combination band with one quantum of the H–C–Cl bend (ν₂) and two quanta of the C–Cl stretch (2ν₃). Rovibrational constants are obtained from least squares fits for each of the four excited vibrational states built on the ν₁ fundamental $$\tilde x$$(100) and the $$\tilde x$$(012) combination mode for each ³⁵Cl and ³⁷Cl atom isotopologue. The four bands occur within a narrow spectral window, requiring detailed comparison of multiple spectral properties (e.g., rotational constant dependence on vibrational excitation, band types/transition dipole moment alignment in the body-fixed frame, etc.) to aid in the vibrational assignment. Indeed, the IR transition intensities arise from strong anharmonic mixing between the “bright” ν₁ C–H stretch and “dark” $$\tilde x$$(012) H–C–Cl bend/C–Cl stretch combination modes, resulting in nearly equal amplitudes for the zeroth order $$\tilde x$$(100) and $$\tilde x$$(012) harmonic states. Lastly, to aid the spectral search for HCCl in the interstellar medium, ground state two-line combination differences are combined with previous laser-induced fluorescence results to predict precision microwave transitions for HC³⁵Cl and HC³⁷Cl.

Authors:

Kortyna, A.  ^[1];

• Search DOE PAGES for author "Kortyna, A."
• Search DOE PAGES for ORCID "0000-0002-8911-6864"

Nesbitt, D. J.  ^[1]

• Search DOE PAGES for author "Nesbitt, D. J."
• Search DOE PAGES for ORCID "0000-0001-5365-1120"

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1. National Inst. of Standards and Technology and Univ.of Colorado, Boulder, CO (United States)

Publication Date:

Fri Aug 17 00:00:00 EDT 2018

Research Org.:

Univ. of Colorado, Boulder, CO (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1540229

Alternate Identifier(s):

OSTI ID: 1464992; OSTI ID: 1924534

Grant/Contract Number:  

SC0002123; FG02-09ER16021

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Chemical Physics

Additional Journal Information:

Journal Volume: 149; Journal Issue: 7; Journal ID: ISSN 0021-9606

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Chemistry; Physics