Solvent cage recombination of 4-benzoylphenylthiyl radicals: Fast intersystem crossing of triplet sulfur-centered radical pairs

Journal Article · Thu Jan 19 04:00:00 EST 1995 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100003a005· OSTI ID:6628419

Autrey, T; Franz, J A ^[1]; Devadoss, C; Sauerwein, B; Schuster, G B ^[2]

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1. Pacific Northwest Lab., Richland, WA (United States)
2. Univ. of Illinois, Urbana, IL (United States)

Picosecond transient absorption spectroscopy was utilized to study the recombination dynamics of triplet sulfur radical pairs. A disulfide, bis(p-benzoylphenyl) disulfide (BpSSBp), was designed to selectively produce triplet thiyl radical pairs by means of internal triplet energy transfer. Thus, irradiation of bis(p-benzoylphenyl) disulfide (BpSSBp) in Tetralin (355 nm, 17 ps) followed by instantaneous singlet - triplet interconversion of the photoexcited benzoyl group leads to rapid intramolecular energy transfer and S - S bond scission. Greater than 50% of the photochemically generated (presumably triplet) radical pairs were found to recombine in competition with cage escape. Benzoyl substitution of phenyl disulfide is expected to cause intersystem crossing (ISC) from the singlet excited state to the triplet state to occur before singlet S - S bond scission can occur. However, benzoyl substitution is not expected to perturb the orbital degeneracy on the thiyl radical that has been suggested to be responsible for the strong spin-orbit coupling mechanism and fast ISC of sulfur-centered radical pairs in micellar solutions. Thus, this study provides the first direct observation of fast ISC (> 100 ps) of sulfur-centered radical pairs in organic solvents. 23 refs., 2 figs.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6628419
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 99:3; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400500 -- Photochemistry
400600* -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
COUPLING
DECOMPOSITION
DISULFIDES
ENERGY TRANSFER
INTERMEDIATE COUPLING
L-S COUPLING
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
RECOMBINATION
SPECTROSCOPY