Temperature and pressure dependent rate coefficients for the reaction of Hg with Cl and the reaction of Cl with Cl

A pulsed laser photolysis-pulsed laser induced fluorescence Study

Deanna L. Donohoue, Dieter Bauer, Anthony J Hynes

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Abstract

A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to study the recombination of mercury and chlorine atoms, Hg + Cl + M → HgCl + M (1), and the self-reaction of chlorine atoms, Cl + Cl + M → Cl 2 + M (2). Rate coefficients were determined as a function of pressure (200-600 Torr) and temperature (243-293 K) in N 2 buffer gas and as a function of pressure (200-600 Torr) in He buffer gas at room temperature. For reaction (1) kinetic measurements were obtained under conditions in which either mercury or chlorine atoms were the reactant in excess concentration while simultaneously monitoring the concentration of both reactants. An Arrhenius expression of (2.2 ± 0.5) × 10 -32 exp{(680 ± 400)(1/T - 1/298)} cm 6 molecule -2 s -1 was determined for the third-order recombination rate coefficient in nitrogen buffer gas. The effective second-order rate coefficient for reaction 1 under atmospheric conditions is much smaller than prior determinations using relative rate techniques. For reaction (2) we obtain an Arrhenius expression of (8.4 ± 2.3) × 10 -33 exp{(850 ± 470)(1/T - 1/298)} cm 6 molecule -2 s -1 for the third-order recombination rate coefficient in nitrogen buffer gas. The rate coefficients are reported with a 2σ error of precision only; however, due to the uncertainty in the determination of absolute chlorine atom concentrations we conservatively estimate an uncertainty of ±50% in the rate coefficients. For both reactions the observed pressure, temperature, and buffer gas dependencies are consistent with the expected behavior for three-body recombination.

Original languageEnglish (US)
Pages (from-to)7732-7741
Number of pages10
JournalJournal of Physical Chemistry A
Volume109
Issue number34
DOIs
StatePublished - Sep 1 2005

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Photolysis
Pulsed lasers
laser induced fluorescence
Chlorine
photolysis
pulsed lasers
Buffers
Gases
Fluorescence
buffers
coefficients
chlorine
Atoms
Mercury
gases
Nitrogen
Temperature
temperature
Molecules
atoms

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

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title = "Temperature and pressure dependent rate coefficients for the reaction of Hg with Cl and the reaction of Cl with Cl: A pulsed laser photolysis-pulsed laser induced fluorescence Study",
abstract = "A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to study the recombination of mercury and chlorine atoms, Hg + Cl + M → HgCl + M (1), and the self-reaction of chlorine atoms, Cl + Cl + M → Cl 2 + M (2). Rate coefficients were determined as a function of pressure (200-600 Torr) and temperature (243-293 K) in N 2 buffer gas and as a function of pressure (200-600 Torr) in He buffer gas at room temperature. For reaction (1) kinetic measurements were obtained under conditions in which either mercury or chlorine atoms were the reactant in excess concentration while simultaneously monitoring the concentration of both reactants. An Arrhenius expression of (2.2 ± 0.5) × 10 -32 exp{(680 ± 400)(1/T - 1/298)} cm 6 molecule -2 s -1 was determined for the third-order recombination rate coefficient in nitrogen buffer gas. The effective second-order rate coefficient for reaction 1 under atmospheric conditions is much smaller than prior determinations using relative rate techniques. For reaction (2) we obtain an Arrhenius expression of (8.4 ± 2.3) × 10 -33 exp{(850 ± 470)(1/T - 1/298)} cm 6 molecule -2 s -1 for the third-order recombination rate coefficient in nitrogen buffer gas. The rate coefficients are reported with a 2σ error of precision only; however, due to the uncertainty in the determination of absolute chlorine atom concentrations we conservatively estimate an uncertainty of ±50{\%} in the rate coefficients. For both reactions the observed pressure, temperature, and buffer gas dependencies are consistent with the expected behavior for three-body recombination.",
author = "Donohoue, {Deanna L.} and Dieter Bauer and Hynes, {Anthony J}",
year = "2005",
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TY - JOUR

T1 - Temperature and pressure dependent rate coefficients for the reaction of Hg with Cl and the reaction of Cl with Cl

T2 - A pulsed laser photolysis-pulsed laser induced fluorescence Study

AU - Donohoue, Deanna L.

AU - Bauer, Dieter

AU - Hynes, Anthony J

PY - 2005/9/1

Y1 - 2005/9/1

N2 - A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to study the recombination of mercury and chlorine atoms, Hg + Cl + M → HgCl + M (1), and the self-reaction of chlorine atoms, Cl + Cl + M → Cl 2 + M (2). Rate coefficients were determined as a function of pressure (200-600 Torr) and temperature (243-293 K) in N 2 buffer gas and as a function of pressure (200-600 Torr) in He buffer gas at room temperature. For reaction (1) kinetic measurements were obtained under conditions in which either mercury or chlorine atoms were the reactant in excess concentration while simultaneously monitoring the concentration of both reactants. An Arrhenius expression of (2.2 ± 0.5) × 10 -32 exp{(680 ± 400)(1/T - 1/298)} cm 6 molecule -2 s -1 was determined for the third-order recombination rate coefficient in nitrogen buffer gas. The effective second-order rate coefficient for reaction 1 under atmospheric conditions is much smaller than prior determinations using relative rate techniques. For reaction (2) we obtain an Arrhenius expression of (8.4 ± 2.3) × 10 -33 exp{(850 ± 470)(1/T - 1/298)} cm 6 molecule -2 s -1 for the third-order recombination rate coefficient in nitrogen buffer gas. The rate coefficients are reported with a 2σ error of precision only; however, due to the uncertainty in the determination of absolute chlorine atom concentrations we conservatively estimate an uncertainty of ±50% in the rate coefficients. For both reactions the observed pressure, temperature, and buffer gas dependencies are consistent with the expected behavior for three-body recombination.

AB - A pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to study the recombination of mercury and chlorine atoms, Hg + Cl + M → HgCl + M (1), and the self-reaction of chlorine atoms, Cl + Cl + M → Cl 2 + M (2). Rate coefficients were determined as a function of pressure (200-600 Torr) and temperature (243-293 K) in N 2 buffer gas and as a function of pressure (200-600 Torr) in He buffer gas at room temperature. For reaction (1) kinetic measurements were obtained under conditions in which either mercury or chlorine atoms were the reactant in excess concentration while simultaneously monitoring the concentration of both reactants. An Arrhenius expression of (2.2 ± 0.5) × 10 -32 exp{(680 ± 400)(1/T - 1/298)} cm 6 molecule -2 s -1 was determined for the third-order recombination rate coefficient in nitrogen buffer gas. The effective second-order rate coefficient for reaction 1 under atmospheric conditions is much smaller than prior determinations using relative rate techniques. For reaction (2) we obtain an Arrhenius expression of (8.4 ± 2.3) × 10 -33 exp{(850 ± 470)(1/T - 1/298)} cm 6 molecule -2 s -1 for the third-order recombination rate coefficient in nitrogen buffer gas. The rate coefficients are reported with a 2σ error of precision only; however, due to the uncertainty in the determination of absolute chlorine atom concentrations we conservatively estimate an uncertainty of ±50% in the rate coefficients. For both reactions the observed pressure, temperature, and buffer gas dependencies are consistent with the expected behavior for three-body recombination.

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