PMID- 18481339
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20080919
LR  - 20080602
IS  - 1439-7641 (Electronic)
IS  - 1439-4235 (Linking)
VI  - 9
IP  - 8
DP  - 2008 Jun 2
TI  - Photodissociation of 1,2-dibromoethylene at 248 nm: Br2 molecular elimination 
      probed by cavity ring-down absorption spectroscopy.
PG  - 1137-45
LID - 10.1002/cphc.200700861 [doi]
AB  - The Br2 elimination channel is probed for 1,2-C2H2Br2 in the 
      B(3)Pi(+)ou-X(1)Sigma(+)g transition upon irradiation at 248 nm by using cavity 
      ring-down absorption spectroscopy (CRDS). The nascent vibrational population 
      ratio of Br2(v=1)/Br2(v=0) is obtained to be 0.7+/-0.2, thus indicating that the 
      Br2 fragment is produced in hot vibrational states. The obtained Br2 products are 
      anticipated to result primarily from photodissociation of the ground-state cis 
      isomer via four-center elimination or from cis/trans isomers via three-center 
      elimination, each mechanism involving a transition state that has a Br-Br 
      distance much larger than that of ground state Br2. According to ab initio 
      potential energy calculations, the pathways that lead to Br2 elimination may 
      proceed either through the electronic ground state by internal conversion or 
      through the triplet state by intersystem crossing. Temperature-dependence 
      measurements are examined, thereby supporting the pathway that involves internal 
      conversion--which was excluded previously by using product translational 
      spectroscopy (PTS). The quantum yield for the Br2 elimination reaction is 
      determined to be 0.120.1, being substantially contributed by the ground-state Br2 
      product. The discrepancy of this value from that (of 0.2) obtained by PTS may 
      rise from the lack of measurements in probing the triplet-state Br2 product.
FAU - Chang, Yuan-Pin
AU  - Chang YP
AD  - Department of Chemistry, National Taiwan University, Taipei.
FAU - Lee, Ping-Chen
AU  - Lee PC
FAU - Lin, King-Chuen
AU  - Lin KC
FAU - Huang, C H
AU  - Huang CH
FAU - Sun, B J
AU  - Sun BJ
FAU - Chang, A H H
AU  - Chang AH
LA  - eng
PT  - Journal Article
PL  - Germany
TA  - Chemphyschem
JT  - Chemphyschem : a European journal of chemical physics and physical chemistry
JID - 100954211
EDAT- 2008/05/16 09:00
MHDA- 2008/05/16 09:01
CRDT- 2008/05/16 09:00
PHST- 2008/05/16 09:00 [pubmed]
PHST- 2008/05/16 09:01 [medline]
PHST- 2008/05/16 09:00 [entrez]
AID - 10.1002/cphc.200700861 [doi]
PST - ppublish
SO  - Chemphyschem. 2008 Jun 2;9(8):1137-45. doi: 10.1002/cphc.200700861.