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Title: Kinetic investigation of the time-resolved atomic fluorescence Ca(4 3P1->4 1S0) and molecular chemiluminescence CaBr(a2-pi, b2-sigma+-]x2-sigma+) following the pulse-dye laser generation of Ca(4 3Pj) in the presence of CH3Br
Authors: Beitia, F * ×
Castano, F *
Rayo, Mns *
Carl, Shaun *
Husain, D *
Santos, L * #
Issue Date: Jan-1991
Publisher: R oldenbourg verlag
Series Title: Zeitschrift fur physikalische chemie-international journal of research in physical chemistry & chemical physics vol:171 pages:137-160
Abstract: The collisional behaviour of the optically metastable, electronically excited state Ca[4s4p(3P(J))], 1.888 eV above its 4s2(1S0) electronic ground state, with the molecule CH3Br, has been studied in the time-domain in order to investigate reactive channels into specific electronic states Ca[4s4p(3P1)] was generated by pulsed dye-laser excitation of calcium vapour at elevated temperatures in the presence of CH3Br and excess helium buffer gas, and the resulting atomic fluorescence at the resonance wavelength {lambda = 657.3 nm, Ca[4s4p(3P1)] --> Ca[4s2(1S0) + hv]} was monitored, following rapid Boltzmann equilibration within the Ca(4(3)P(J)) spin-orbit manifold, using Boxcar Integration. The electronically excited atom exhibited exponential decay profiles which were characterised. Time-resolved chemiluminescence was also monitored under identical conditions for both the CaBr(A2-PI-1/2,3/2 --> X2-SIGMA+) and CaBr(B2-SIGMA+ --> X2-SIGMA+) systems, principally via the (0,0) transitions, on account of Franck-Condon limitations. These molecular emissions exhibit decay profiles which are principally single-exponential in form after a short delay and equal in magnitude to those from Ca(4(3)P(J)). In the case of the A - X chemiluminescence, it was possible under some conditions to resolve the spin-orbit components of the (0,0) transitions for A2-PI-1/2 and A2-PI-3/2 --> X2-SIGMA+ whose exponential decay coefficients were also found to be equal in magnitude, and thus indicating that these also are in equilibrium during the kinetic decays. The exponential form and equality in the decay coefficients for the atomic and both A - X and B - X chemiluminescence profiles are in accord with a mechanism involving the production of these electronically excited states by direct reaction: Ca(4(3)P(J)) + CH3Br --> CaBr(A2-PI-1/2,3/2, upsilon' less-than-or-equal-to 2) + CH3 (k2) (2) Ca(4(3)P(J)) + CH3Br --> CaBr(B2-SIGMA+, upsilon' = 0) + CH3 (k3). (3)
ISSN: 0942-9352
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Quantum Chemistry and Physical Chemistry Section
* (joint) first author
× corresponding author
# (joint) last author

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