William G. Becker

Photochemistry of ultrahigh laboratory magnetic fields. Photolysis of micellar solutions of dibenzyl ketones and phenyl benzyl ketones at 145 000 G. Observation of a .DELTA.g.vector.H effect on the cage reaction

Experiments are described that were carried out to determine whether the reactions of solvated triplet radical pairs in micelle cages are determined by Zeeman-induced mixing at ultrahigh magnetic fields. Dibenzyl ketone and phenyibenzyl ketones were studied as prototypes, and data are tabulated for magnetic field effects in the cage reactions of para-monosubstituted dibenzyl ketones. The noted result that the percent cage is the same at low field and at ultrahigh fields is interpreted to mean that a new mechanism, spin-orbit coupling, dominates the reversible singlet ..-->.. triplet intersystem crossing in molecules. Data are also tabulated to show the influence of applied field strength on the percent cage produced in the photolysis of 1,2-diphenyl-2-methylpropanone and some of its isotopically substituted derivatives. From the data presented, it is concluded that the extent of cage recombination of benzyl radicals and/or substituted benzyl radical pairs produced in micelle aggregates depends on the strength of the external laboratory field applied to the samples. 21 references, 1 figure, 2 tables. (BLM)

Electrogenerated chemiluminescence: Part XLIII. Aromatic hydrocarbon/peroxydisulfate systems in acetonitrile-benzene solutions

Abstract Electrogenerated chemiluminescence (ECL) has been observed during the reduction of peroxydisulfate (S 2 O 8 2− ) by electrogenerated radical anions of several aromatic compounds (Ar − ) in 2:1 CH 3 CN-benzene solutions. The ECL spectra that arise at the Ar reduction wave agree with the fluorescence spectra of the corresponding aromatic compound. The cyclic voltammetric Ar reduction waves in the presence of S 2 O 8 2− were generally of the catalytic type, with Ar regenerated by the following chemical reaction with peroxydisulfate. Formation of Ar ★ with the resulting ECL was primarily caused by the Ar − /Ar + reaction, with Ar + generated via oxidation of Ar by SO 4 − (a product of the reduction of S 2 O 8 2− ). The relative ECL efficiencies qualitatively depend upon the stability of the hydrocarbon radical cations, with rubrene producing the most intense ECL. A tertiary reactant system in which thianthrene fluorescence was observed during the catalyzed reduction of S 2 O 8 2− by the radical anion 2,5-diphenyl-1,3,4-oxadizole was also studied.

Photochemistry in ultrahigh laboratory magnetic fields. Photolysis of micellar solutions of dibenzyl ketones and phenyibenzyl ketones at 145,000 G. Observation of a. delta. gH effect on the cage reaction

Experiments are described that were carried out to determine whether the reactions of solvated triplet radical pairs in micelle cages are determined by Zeeman-induced mixing at ultrahigh magnetic fields. Dibenzyl ketone and phenyibenzyl ketones were studied as prototypes, and data are tabulated for magnetic field effects in the cage reactions of para-monosubstituted dibenzyl ketones. The noted result that the percent cage is the same at low field and at ultrahigh fields is interpreted to mean that a new mechanism, spin-orbit coupling, dominates the reversible singlet ..-->.. triplet intersystem crossing in molecules. Data are also tabulated to show the influence of applied field strength on the percent cage produced in the photolysis of 1,2-diphenyl-2-methylpropanone and some of its isotopically substituted derivatives. From the data presented, it is concluded that the extent of cage recombination of benzyl radicals and/or substituted benzyl radical pairs produced in micelle aggregates depends on the strength of the external laboratory field applied to the samples. 21 references, 1 figure, 2 tables. (BLM)

Photochemistry in ultrahigh laboratory magnetic fields. Photolysis of micellar solutions of dibenzyl ketones at 145,000 G. observation of a. delta. g vector H effect on the cage reaction

Experiments are described that were carried out to determine whether the reactions of solvated triplet radical pairs in micelle cages are determined by Zeeman-induced mixing at ultrahigh magnetic fields. Dibenzyl ketone and phenyibenzyl ketones were studied as prototypes, and data are tabulated for magnetic field effects in the cage reactions of para-monosubstituted dibenzyl ketones. The noted result that the percent cage is the same at low field and at ultrahigh fields is interpreted to mean that a new mechanism, spin-orbit coupling, dominates the reversible singlet ..-->.. triplet intersystem crossing in molecules. Data are also tabulated to show the influence of applied field strength on the percent cage produced in the photolysis of 1,2-diphenyl-2-methylpropanone and some of its isotopically substituted derivatives. From the data presented, it is concluded that the extent of cage recombination of benzyl radicals and/or substituted benzyl radical pairs produced in micelle aggregates depends on the strength of the external laboratory field applied to the samples. 21 references, 1 figure, 2 tables. (BLM)