Inverse temperature dependences in the quenching of singlet oxygen O/sub 2/(/sup 1/. sigma. /sup +//sub g/) by CO/sub 2/ and N/sub 2/O studied with a discharge flow/shock tube
The rates of quenching of O/sub 2/(/sup 1/..sigma../sup +//sub g/) by CO/sub 2/ and N/sub 2/O have been measured at 293 K and between 600 and 1300 K by studying the time-resolved emission in a discharge flow/shock tube experiment. For CO/sub 2/, the quenching constant rises slightly from 2.09 +- 0.23 x 10/sup 8/ dm/sup 3/ mol/sup -1/ s/sup -1/ at 293 K to a maximum and then falls to 1.44 x 10/sup 7/ dm/sup 3/ mol/sup -1/ s/sup -1/ at 1300 K. The behavior for N/sub 2/O is similar, rising slightly from 5.89 +- 0.25 x 10/sup 7/ dm/sup 3/ mol/sup -1/ s/sup -1/ at 293 K and falling to 1.65 x 10/sup 7/ dm/sup 3/ mol/sup -1/ s/sup -1/ at 1250 K. The detailed results are given in Figs. 5 and 8. The low temperature results agree well with previous work. A comparison is made of the decline in rate with the model of Parmenter, which unfortunately does not fit, although his suggested correlation of cross section with well depth is reasonable at room temperature. It is suggested that various temperature dependences found for these and other quenchers indicate that curve crossing occurs in those systems close to the potential energy minimum and so makes the rates very sensitive to the nature of the quenching molecule. An additional emission is found at longer times in the N/sub 2/O system, which is attributed to chemiluminescence from NO/sub 2/ formed by decomposition of N/sub 2/O.
- Research Organization:
- Department of Chemistry, Keele University, Keele, Straffordshire, England ST5 5BG
- OSTI ID:
- 6525999
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 78:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
MOLECULE-MOLECULE COLLISIONS
NITROUS OXIDE
OXYGEN
CHEMILUMINESCENCE
EMISSION SPECTRA
ENERGY TRANSFER
HIGH TEMPERATURE
KINETICS
RADIATIONLESS DECAY
TEMPERATURE DEPENDENCE
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
DE-EXCITATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
LUMINESCENCE
MOLECULE COLLISIONS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
SPECTRA
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena