Actinometry in monochromatic flash photolysis: the extinction coefficient of triplet benzophenone and quantum yield of triplet zinc tetraphenyl porphyrin

Technical Report · Mon Nov 15 04:00:00 EST 1982

OSTI ID:6581787

Hurley, J K; Sinai, N; Linschitz, H

The extinction coefficient epsilon/sub T/, of triplet benzophenone in benzene has been directly determined by absolute measurements of absorbed energy and triplet absorbance, ..delta..D/sup 0//sub T/, under demonstrably linear conditions where incident excitation energy, E/sub 0/, and ground state absorbance, A/sub 0/, are both extrapolated to zero. The result, 7220 +- 320 M/sup -1/ cm/sup -1/ at 530 nm, validates and corrects many measurements of triplet and radical extinctions and yields, using the energy-transfer method. As E/sub 0/ and A/sub 0/ both decrease, ..delta..D/sup 0//sub T/ becomes proportional to their product. In this situation, the ratio R = (1/A/sub 0/) (d..delta..D/sup 0//sub T//dE/sub 0/) = (epsilon/sub T/ /sup -/ epsilon/sub G/)phi/sub T/. Measurements of R, referred to benzophenone, give (epsilon/sub T/ - epsilon/sub G/)phi/sub T/ for any substance, without necessity for absolute energy calibration. Both absolute and relative laser flash measurements on zinc tetraphenyl porphyrin (epsilon/sub T/ - epsilon/sub G/ at 470 nm = 7.3 x 10/sup 4/ M/sup -1/ cm/sup -1/) give phi/sub T/ = 0.83 +- 0.04. 6 figures, 2 tables.

• Research Organization: Brandeis Univ., Waltham, MA (USA). Dept. of Chemistry
• DOE Contract Number: AC02-76ER03117
• OSTI ID: 6581787
• Report Number(s): DOE/ER/03117-25; COO-3117-25; ON: DE83006819
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION
AROMATICS
BENZENE
BENZOPHENONE
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
IRRADIATION
KETONES
LASER RADIATION
MULTIPLETS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PORPHYRINS
PULSED IRRADIATION
RADIATIONS
TRIPLETS
ZINC COMPOUNDS