Flash photolysis of transient radicals. 1. X/sub 2//sup -/ with X = Cl, Br, I, and SCN
The radicals Cl/sub 2//sup -/, Br/sub 2//sup -/, I/sub 2//sup -/, and (SCN)/sub 2//sup -/ were prepared by photolysis of appropriate chemical systems with one laser and were subsequently photolyzed with a second laser. The first three species were photolyzed at 355 nm, and (SCN)/sub 2//sup -/ was photolyzed at 532 nm, I/sub 2//sup -/ was also photolyzed at 700 nm. In each case, dissociation into the fragments X and X/sup -/ was detected by a bleach in the absorption of X/sub 2//sup -/. In no case was electron photodetachment observed. Observation of the recovery of the original absorption allowed the corresponding rate constant to be measured. In the case of Cl/sub 2//sup -/ the bleach in absorption does not completely recovery and the loss of absorption is dose dependent. Because the presence of acid allows a more complete recovery, it can be concluded that the product Cl atom is photolyzed by a second photon to produce OH and Cl/sup -/. This photoreaction is direct experimental evidence that the absorption band of Cl involves charge transfer from solvent. Detailed analysis of the bleaching and recovery behavior at high Cl/sup -/ concentrations showed no time lag which could be attributed to the /sup 2/P/sub 1/2/ Cl atom, implying a short lifetime for this species. 13 references, 6 figures, 2 tables.
- Research Organization:
- Univ. of Notre Dame, IN
- OSTI ID:
- 5102857
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 89:11
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
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ABSORPTION SPECTROSCOPY
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PHOTOLYSIS
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POTASSIUM BROMIDES
POTASSIUM COMPOUNDS
POTASSIUM IODIDES
SODIUM CHLORIDES
THIOCYANATES
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
DISSOCIATION
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PH VALUE
VISIBLE RADIATION
ALKALI METAL COMPOUNDS
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CHEMISTRY
CHLORINE COMPOUNDS
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DRUGS
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HALOGEN COMPOUNDS
HORMONE ANTAGONISTS
INFORMATION
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IODINE COMPOUNDS
KINETICS
MIXTURES
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ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOSPHORS
PHOTOCHEMICAL REACTIONS
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400500* - Photochemistry