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Titolo:
Determination of the branching ratios of CaBr(A(2)Pi(1/2,3/2),B-2 Sigma(+)) resulting from the reaction of Ca[4s4p(P-3(J))] with CH3Br by time-resolved atomic emission and molecular chemiluminescence following pulsed dye-laser excitation of atomic calcium
Autore:
Husain, D; Geng, J; Castano, F; Rayo, MNS;
Indirizzi:
Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England Univ Cambridge Cambridge England CB2 1EW hem, Cambridge CB2 1EW, England Univ Pais Vasco, Dept Quim Fis, E-48080 Bilbao, Spain Univ Pais Vasco Bilbao Spain E-48080 ept Quim Fis, E-48080 Bilbao, Spain
Titolo Testata:
ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS
, volume: 215, anno: 2001,
parte:, 5
pagine: 547 - 560
SICI:
0942-9352(2001)215:<547:DOTBRO>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
SPIN-ORBIT STATE; RESONANCE FLUORESCENCE SR(5(3)P(1)->5(1)S(0)); RADIATIVE LIFETIMES; CHEMI-LUMINESCENCE; GENERATION; CA(43P1->41S0); SR(5(3)P(J)); CA(43PJ); ENERGY; B-2-SIGMA(+)->X(2)SIGMA(+));
Keywords:
molecular electronic branching ratios; CaBr(A(2)Pi(1/2)), CaBr(A(2)Pi(3/2)), CaBr(B-2 Sigma(+)); time-resolved atomic emission and molecular chemiluminescence; dye-laser excitation of Ca(P-3(J)); Ca(P-3(J)) + CH3Br collisions;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Husain, D Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England Univ Cambridge Lensfield Rd Cambridge England CB2 1EW , England
Citazione:
D. Husain et al., "Determination of the branching ratios of CaBr(A(2)Pi(1/2,3/2),B-2 Sigma(+)) resulting from the reaction of Ca[4s4p(P-3(J))] with CH3Br by time-resolved atomic emission and molecular chemiluminescence following pulsed dye-laser excitation of atomic calcium", Z PHYS CHEM, 215, 2001, pp. 547-560

Abstract

Molecular electronic branching ratios to yield CaBr(A(2)Pi (1/2)), CaBr(A(2)Pi (3/2)) and CaBr(B(2)Sigma (+)) have been determined in the time-domainfollowing the reaction of Ca[4s4p(P-3(j))], 1.888eV above the 4s(2)(S-1(0)) ground state. with CH3Br. Ca[4s4p(P-3(1))] was generated by the pulsed dye-laser excitation of ground state calcium atoms at lambda = 657.3 nm {Ca[4s4p(P-3(1))]-->Ca[4s(2)(S-1(0))]} at elevated temperatures in the presence of CH3Br and excess helium buffer gas. Measurements were then made of the atomic resonance fluorescence from Ca(4(3)P(1)--> 4(1)S(0)), and the molecular chemiluminescence from CaBr(A(2)Pi (1/2), A(2)Pi (3/2), B(2)Sigma (+) --> X(2)Sigma (+)) after Boltzmann equilibration with Ca(4(3)P(0,1,2)). The following molecular chemiluminescence emissions were recorded: CaBr(A(2)Pi (1/2) -->X(2)Sigma (+) = Deltav = 0, lambda = 628 nm), CaBr(A(2)Pi (3/2) -->X(2)Sigma (+), Deltav = 0, lambda = 625 nm) and CaBr(B(2)Sigma (+) --> X(2)Sigma+, Deltav = 0, h = 611 nm). The atomic and molecular emissions demonstrated exponential decays characterised by decay coefficients which were equal under identical chemical conditions thus demonstrating the production of CaBr(A(2)Pi (1/2.3/2), B(2)Sigma (+)) by direct reaction of Ca(P-3(j)) with CH3Br. The combination of the time-dependences of the atomic and molecular profiles together with the integrated atomic and molecular intensities, placed on a common intensity scale by calibration of the optical system against a spectral radiometer, yielded branching ratios into the A(2)Pi (1/2),A(2)Pi (3/2) and B(2)Sigma (+) states of CaBr. These were found to be as follows: A(1/2) (9.8 +/- 3.0) . 10(4); A(3/2 0)(8.5 +/- 3.4) . 10(-4) and B,(3.4 +/- 1.7) . 10(-4). To the best of our knowledge, these data representthe first measurements of electronic branching ratios of calcium bromide into specific molecular states for reactions of Ca(4(3)P(J)). The results are compared with various related data for total branching ratios into electronic states studied in the single collision condition for this atomic statewith CH3Br using molecular beams, and with analogous measurements for Ca(4P-3(J)) + CH3F and CH3Cl. These results are also compared with branching ratios of SrBr(A(2)Pi (1/2), A(2)Pi (3/2), B(2)Sigma (+)) following the reaction of Sr[5s5p(P-3(J))] + CH2Br2 investigated following pulsed dye-laser generation of Sr(5 P-3(J)).

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/04/20 alle ore 09:08:45