Evidence of exciplex formation in acetonitrile

✍ Scribed by Koichi Kikuchi; Taeko Niwa; Yasutake Takahashi; Hiroshi Ikeda; Tsutomu Miyashi; Masato Hoshi

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 306 KB
• Volume: 173
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(90)87227-i

✦ Synopsis

Fluorescence spectra and lifetimes were measured in acetonitrile using anthracenecarbonitriles as the fluorescent material and aromatic compounds as the quencher. Exciplex fluorescence was observed for several systems when their free enthalpy change AG, of the actual electron transfer (ET) of the fluorescence quenching is in the range -0.28 to SO.20 eV. It may be concluded for these systems that ET fluorescence quenching is not due to full ET in the encounter state between the fluorescent material and the quencher, but predominantly due to partial ET, i.e. exciplex formation, through which free radicals may also be produced. This means that the ET theory, which assumes a weak electronic exchange interaction between the electron &nor and acceptor, is not necessarily available for the theoretical explanation of the free enthalpy dependence of the fluorescence quenching rate in the normal region.