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Detection of triplet—triplet absorption in microcrystalline benzophenone by diffuse-reflectance laser flash photolysis

✍ Scribed by F. Wilkinson; C.J. Willsher

Publisher
Elsevier Science
Year
1984
Tongue
English
Weight
327 KB
Volume
104
Category
Article
ISSN
0009-2614

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✦ Synopsis

An apparatus is described which can detect transient absorptions in the nanosecond-microsecond time domain in opaque scattering materials by analysing diffusely reflected monitoring light following nanosecond laser excitation. For microcrystalline benzophenone excited by a 20 ns pulse at 354 nm, a transient absorption is easily recorded, having a maximum at 540 nm. Its decay is a mixture of first-and second-order processes, with the initial and final slopes of the first-order kinetic analysis differing by a factor of 10. The second-order rate constant is estimated to be (8.5 +-1.0) × 109 cm 3 moV 1 s q . Microcrystalline benzophenone emits a phosphorescence which, within experimental error, has an identical kinetic decay.

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