Absorption Spectra and Dynamics of the Triplet State in p -Terphenyl Powder Systems: a Diffuse Reflectance Laser Photolysis Study

Abstract

A microcomputer-controlled nanosecond diffuse reflectance laser photolysis system was developed and applied to p-terphenyl powder systems. The triplet absorption spectrum of microcrystalline powders is broader and red-shifted compared to the molecular triplet state in solution. Possible contributions of an optical artifact and an impurity were rejected by examining powder systems doped with naphthacene and diluted with NaCl as well as poly(methyl methacrylate). p-Terphenyl adsorbed on silica gel and included in β-cyclodextrin gave different triplet spectra, which are interpreted in terms of conformational structure of p-terphenyl. Decay processes and an oxygen effect are also discussed.