Reinvestigation of the laser-initiated Cl/sub 2//HBr chain reaction: absolute rate constants and the v = 2/v = 1 ratio from Cl + HBr. -->. HCl(v) + Br

Journal Article · Thu Jun 18 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100297a016· OSTI ID:6036910

Dolson, D A; Leone, S R

The Cl/sub 2//HBr chain reaction is reinvestigated by using real time state-selected observations of ..delta..v = -1 chemiluminescence from the HCl(V) products following pulsed laser photolysis of Cl/sub 2/. These state-selected observations are analyzed with a more complete kinetic treatment to obtain room temperature rate constants for the chain propagation steps and the vibrational deactivation of HCl(V = 1,2) by HBr. The chain propagation rate constants are k/sub R1/ = (1.02 +/- 0.15) x 10/sup -11/ and k/sub R2/ = (1.1 +/- 0.4) x 10/sup -15/ cm/sup 3/ molecule/sup -1/ s/sup -1/, respectively, for Cl + HBr ..-->../sup kR1/ HCl(v) + Br and Br + Cl/sub 2/ ..-->../sup kR2/ BrCl + Cl. Rate constants for vibrational deactivation of HCl(v=1) and HCl(v=2) by HBr are k/sub V1/ = (1.06 +/- 0.16) x 10/sup -12/ and k/sub V2/ = (2.09 +/- 0.50) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. Relative intensity measurements of the HCl v = 2 ..-->.. 1 and 1 ..-->.. 0 vibrational fluorescence are used to obtain an HCl(v) product branching ratio, N/sub v=2//N/sub v=1/ = 0.40 +/- 0.06. The kinetic analysis indicates that broad-band observations of infrared chemiluminescence may lead to erroneous rate constant determinations because of vibrational cascade, whereas the detection of individual vibrational states leads to correct results.

• Research Organization: Univ. of Colorado, Boulder
• OSTI ID: 6036910
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:13; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMILUMINESCENCE
CHLORINE
DATA
DECOMPOSITION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HALOGENS
HYDROBROMIC ACID
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
KINETICS
LASERS
LUMINESCENCE
MEDIUM TEMPERATURE
NONMETALS
NUMERICAL DATA
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PULSE TECHNIQUES
REACTION KINETICS
VIBRATIONAL STATES