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Title: The near-infrared spectrum of ethynyl radical

Abstract

Transient diode laser absorption spectroscopy has been used to measure three strong vibronic bands in the near infrared spectrum of the C{sub 2}H, ethynyl, radical not previously observed in the gas phase. The radical was produced by ultraviolet excimer laser photolysis of either acetylene or (1,1,1)-trifluoropropyne in a slowly flowing sample of the precursor diluted in inert gas, and the spectral resolution was Doppler-limited. The character of the upper states was determined from the rotational and fine structure in the observed spectra and assigned by measurement of ground state rotational combination differences. The upper states include a {sup 2}Σ{sup +} state at 6696 cm{sup −1}, a second {sup 2}Σ{sup +} state at 7088 cm{sup −1}, and a {sup 2}Π state at 7110 cm{sup −1}. By comparison with published calculations [R. Tarroni and S. Carter, J. Chem. Phys 119, 12878 (2003); Mol. Phys. 102, 2167 (2004)], the vibronic character of these levels was also assigned. The observed states contain both X{sup 2}Σ{sup +} and A{sup 2}Π electronic characters. Several local rotational level perturbations were observed in the excited states. Kinetic measurements of the time-evolution of the ground state populations following collisional relaxation and reactive loss of the radicals formed in amore » hot, non-thermal, population distribution were made using some of the strong rotational lines observed. The case of C{sub 2}H may be a good place to investigate the behavior at intermediate pressures of inert colliders, where the competition between relaxation and reaction can be tuned and observed to compare with master equation models, rather than deliberately suppressed to measure thermal rate constants.« less

Authors:
;  [1];  [1];  [2]
  1. Department of Energy and Photon Sciences, Division of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22678962
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; EXCIMER LASERS; EXCITED STATES; FINE STRUCTURE; FLUORINE COMPOUNDS; GROUND STATES; INFRARED SPECTRA; PERTURBATION THEORY; RADICALS; REACTION KINETICS; RELAXATION LOSSES

Citation Formats

Le, Anh T., E-mail: anhle@bnl.gov, Hall, Gregory E., E-mail: gehall@bnl.gov, Sears, Trevor J., E-mail: sears@bnl.gov, E-mail: trevor.sears@stonybrook.edu, and Chemistry Department, Stony Brook University, Stony Brook, New York 11794. The near-infrared spectrum of ethynyl radical. United States: N. p., 2016. Web. doi:10.1063/1.4961019.
Le, Anh T., E-mail: anhle@bnl.gov, Hall, Gregory E., E-mail: gehall@bnl.gov, Sears, Trevor J., E-mail: sears@bnl.gov, E-mail: trevor.sears@stonybrook.edu, & Chemistry Department, Stony Brook University, Stony Brook, New York 11794. The near-infrared spectrum of ethynyl radical. United States. https://doi.org/10.1063/1.4961019
Le, Anh T., E-mail: anhle@bnl.gov, Hall, Gregory E., E-mail: gehall@bnl.gov, Sears, Trevor J., E-mail: sears@bnl.gov, E-mail: trevor.sears@stonybrook.edu, and Chemistry Department, Stony Brook University, Stony Brook, New York 11794. 2016. "The near-infrared spectrum of ethynyl radical". United States. https://doi.org/10.1063/1.4961019.
@article{osti_22678962,
title = {The near-infrared spectrum of ethynyl radical},
author = {Le, Anh T., E-mail: anhle@bnl.gov and Hall, Gregory E., E-mail: gehall@bnl.gov and Sears, Trevor J., E-mail: sears@bnl.gov, E-mail: trevor.sears@stonybrook.edu and Chemistry Department, Stony Brook University, Stony Brook, New York 11794},
abstractNote = {Transient diode laser absorption spectroscopy has been used to measure three strong vibronic bands in the near infrared spectrum of the C{sub 2}H, ethynyl, radical not previously observed in the gas phase. The radical was produced by ultraviolet excimer laser photolysis of either acetylene or (1,1,1)-trifluoropropyne in a slowly flowing sample of the precursor diluted in inert gas, and the spectral resolution was Doppler-limited. The character of the upper states was determined from the rotational and fine structure in the observed spectra and assigned by measurement of ground state rotational combination differences. The upper states include a {sup 2}Σ{sup +} state at 6696 cm{sup −1}, a second {sup 2}Σ{sup +} state at 7088 cm{sup −1}, and a {sup 2}Π state at 7110 cm{sup −1}. By comparison with published calculations [R. Tarroni and S. Carter, J. Chem. Phys 119, 12878 (2003); Mol. Phys. 102, 2167 (2004)], the vibronic character of these levels was also assigned. The observed states contain both X{sup 2}Σ{sup +} and A{sup 2}Π electronic characters. Several local rotational level perturbations were observed in the excited states. Kinetic measurements of the time-evolution of the ground state populations following collisional relaxation and reactive loss of the radicals formed in a hot, non-thermal, population distribution were made using some of the strong rotational lines observed. The case of C{sub 2}H may be a good place to investigate the behavior at intermediate pressures of inert colliders, where the competition between relaxation and reaction can be tuned and observed to compare with master equation models, rather than deliberately suppressed to measure thermal rate constants.},
doi = {10.1063/1.4961019},
url = {https://www.osti.gov/biblio/22678962}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 7,
volume = 145,
place = {United States},
year = {Sun Aug 21 00:00:00 EDT 2016},
month = {Sun Aug 21 00:00:00 EDT 2016}
}

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Works referencing / citing this record:

Kinetic study of the OH + ethylene reaction using frequency‐modulated laser absorption spectroscopy
journal, April 2019