skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels (X {sup 2}{sigma}{sup +}, v=2, N=0, 1, 6, 10, 15, and 20) and C{sub 2}H{sub 2}

Abstract

Rate coefficients (k{sub tot,N{sub i}}) are reported (a) for total removal (reactive+inelastic) of CN(X {sup 2}{sigma}{sup +},v=2,N{sub i}) radicals from selected rotational levels (N{sub i}=0, 1, 6, 10, 15, and 20) and (b) for state-to-state rotational energy transfer (k{sub i{yields}}{sub f}) between levels N{sub i} and other rotational levels N{sub f} in collisions with C{sub 2}H{sub 2}. CN radicals were generated by pulsed laser photolysis of NCNO at 573 nm. A fraction of the radicals was then promoted to a selected rotational level in v=2 using a tunable infrared ''pump'' laser operating at {approx}2.45 {mu}m, and the subsequent fate of this subset of radicals was monitored using pulsed laser-induced fluorescence (PLIF). Values of k{sub tot,N{sub i}} were determined by observing the decay of the PLIF signals as the delay between pump and probe laser pulses was systematically varied. In a second series of experiments, double resonance spectra were recorded at a short delay between the pump and probe laser pulses. Analysis of these spectra yielded state-to-state rate coefficients for rotational energy transfer, k{sub i{yields}}{sub f}. The difference between the sum of these rate coefficients, {sigma}{sub f}k{sub i{yields}}{sub f}, and the value of k{sub tot,N{sub i}} for the same level N{submore » i} is attributed to the occurrence of chemical reaction, yielding values of the rotationally selected rate coefficients (k{sub reac,N{sub i}}) for reaction of CN from specified rotational levels. These rate coefficients decrease from (7.9{+-}2.2)x10{sup -10} cm{sup 3}molecule{sup -1} s{sup -1} for N{sub i}=0 to (0.8{+-}1.3)x10{sup -10} cm{sup 3} molecule{sup -1} s{sup -1} for N{sub i}=20. The results are briefly discussed in the context of microcanonical transition state theory and the statistical adiabatic channel model.« less

Authors:
;  [1]
  1. University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW (United Kingdom)
Publication Date:
OSTI Identifier:
20991244
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 126; Journal Issue: 13; Other Information: DOI: 10.1063/1.2715594; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBON NITRIDES; ENERGY TRANSFER; FLUORESCENCE; LASER RADIATION; MOLECULE-MOLECULE COLLISIONS; ORGANIC COMPOUNDS; PHOTOLYSIS; PULSED IRRADIATION; RADICALS; REACTION KINETICS; ROTATIONAL STATES; SPECTRA

Citation Formats

Olkhov, Rouslan V., and Smith, Ian W. M. Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels (X {sup 2}{sigma}{sup +}, v=2, N=0, 1, 6, 10, 15, and 20) and C{sub 2}H{sub 2}. United States: N. p., 2007. Web. doi:10.1063/1.2715594.
Olkhov, Rouslan V., & Smith, Ian W. M. Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels (X {sup 2}{sigma}{sup +}, v=2, N=0, 1, 6, 10, 15, and 20) and C{sub 2}H{sub 2}. United States. doi:10.1063/1.2715594.
Olkhov, Rouslan V., and Smith, Ian W. M. Sat . "Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels (X {sup 2}{sigma}{sup +}, v=2, N=0, 1, 6, 10, 15, and 20) and C{sub 2}H{sub 2}". United States. doi:10.1063/1.2715594.
@article{osti_20991244,
title = {Rate coefficients for reaction and for rotational energy transfer in collisions between CN in selected rotational levels (X {sup 2}{sigma}{sup +}, v=2, N=0, 1, 6, 10, 15, and 20) and C{sub 2}H{sub 2}},
author = {Olkhov, Rouslan V. and Smith, Ian W. M.},
abstractNote = {Rate coefficients (k{sub tot,N{sub i}}) are reported (a) for total removal (reactive+inelastic) of CN(X {sup 2}{sigma}{sup +},v=2,N{sub i}) radicals from selected rotational levels (N{sub i}=0, 1, 6, 10, 15, and 20) and (b) for state-to-state rotational energy transfer (k{sub i{yields}}{sub f}) between levels N{sub i} and other rotational levels N{sub f} in collisions with C{sub 2}H{sub 2}. CN radicals were generated by pulsed laser photolysis of NCNO at 573 nm. A fraction of the radicals was then promoted to a selected rotational level in v=2 using a tunable infrared ''pump'' laser operating at {approx}2.45 {mu}m, and the subsequent fate of this subset of radicals was monitored using pulsed laser-induced fluorescence (PLIF). Values of k{sub tot,N{sub i}} were determined by observing the decay of the PLIF signals as the delay between pump and probe laser pulses was systematically varied. In a second series of experiments, double resonance spectra were recorded at a short delay between the pump and probe laser pulses. Analysis of these spectra yielded state-to-state rate coefficients for rotational energy transfer, k{sub i{yields}}{sub f}. The difference between the sum of these rate coefficients, {sigma}{sub f}k{sub i{yields}}{sub f}, and the value of k{sub tot,N{sub i}} for the same level N{sub i} is attributed to the occurrence of chemical reaction, yielding values of the rotationally selected rate coefficients (k{sub reac,N{sub i}}) for reaction of CN from specified rotational levels. These rate coefficients decrease from (7.9{+-}2.2)x10{sup -10} cm{sup 3}molecule{sup -1} s{sup -1} for N{sub i}=0 to (0.8{+-}1.3)x10{sup -10} cm{sup 3} molecule{sup -1} s{sup -1} for N{sub i}=20. The results are briefly discussed in the context of microcanonical transition state theory and the statistical adiabatic channel model.},
doi = {10.1063/1.2715594},
journal = {Journal of Chemical Physics},
number = 13,
volume = 126,
place = {United States},
year = {Sat Apr 07 00:00:00 EDT 2007},
month = {Sat Apr 07 00:00:00 EDT 2007}
}