TY - JOUR
T1 - Temperature dependences of singlet methylene removal rates
AU - Hayes, Frances
AU - Lawrance, Warren D.
AU - Staker, Warren S.
AU - King, Keith D.
PY - 1996/1/1
Y1 - 1996/1/1
N2 - The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, 1CH2 (ã 1A1), in the temperature range 298-462 K. The temperature dependences of the removal rate constants for N2, CH4, C2H4, C2H6, H2O, H2CO, CH2CO, CH3F, C2F6, and CH3OH were measured and the Arrhenius parameters determined. For the reacting species, CH4, C2H4, C2H6, H2O, H2CO, CH2CO, CH3F, and CH3OH, the rate constants exhibit negative temperature dependences with activation energies covering the range -0.7 ± 0.7 kJ mol-1 for CH3F to -3.5 ± 1.0 kJ mol-1 for CH3OH. In contrast, positive temperature dependences are observed for the nonreacting species, N2 and C2F6, with activation energies of 1.8 ± 0.9 and 1.6 ± 2.0 kJ mol-1, respectively. Good agreement was obtained with previously reported measurements for the N2, CH4, CH2CO, C2H4, and C2H6 temperature dependences. For the nonreacting species, comparison is made with theoretical predicted temperature dependences for collision-induced intersystem crossing from 1CH2 (ã 1A1) to 3CH2 (X̃ 3B1).
AB - The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, 1CH2 (ã 1A1), in the temperature range 298-462 K. The temperature dependences of the removal rate constants for N2, CH4, C2H4, C2H6, H2O, H2CO, CH2CO, CH3F, C2F6, and CH3OH were measured and the Arrhenius parameters determined. For the reacting species, CH4, C2H4, C2H6, H2O, H2CO, CH2CO, CH3F, and CH3OH, the rate constants exhibit negative temperature dependences with activation energies covering the range -0.7 ± 0.7 kJ mol-1 for CH3F to -3.5 ± 1.0 kJ mol-1 for CH3OH. In contrast, positive temperature dependences are observed for the nonreacting species, N2 and C2F6, with activation energies of 1.8 ± 0.9 and 1.6 ± 2.0 kJ mol-1, respectively. Good agreement was obtained with previously reported measurements for the N2, CH4, CH2CO, C2H4, and C2H6 temperature dependences. For the nonreacting species, comparison is made with theoretical predicted temperature dependences for collision-induced intersystem crossing from 1CH2 (ã 1A1) to 3CH2 (X̃ 3B1).
UR - http://www.scopus.com/inward/record.url?scp=33748443383&partnerID=8YFLogxK
U2 - 10.1021/jp960002z
DO - 10.1021/jp960002z
M3 - Article
AN - SCOPUS:33748443383
SN - 0022-3654
VL - 100
SP - 11314
EP - 11318
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 27
ER -