PHOTOIONIZATION OF DIARYLMETHYL RADICALS IN ACETONITRILE AND ALCOHOL WATER - LASER FLASH PRODUCTION OF DIARYLCARBENIUM IONS

• Tipo: Artigo em Revista Científica Internacional
• Data: 1993

Autores

Faria, JL (Autor) FEUP; Steenken, S (Autor) Outra

Revista

Título: Journal of Physical Chemistry

Vol. 97

Páginas: 1924-1930

ISSN: 0022-3654

Editora: American Chemical Society

Indexação

ISI Web of Knowledge - 48 Citações

Scopus - 49 Citações

Outras Informações

ID Authenticus: P-008-NY8

DOI: 10.1021/j100111a034

Abstract (EN): Diarylmethyl radicals Ar2CH¿ were produced by 248-nm laser photolysis (20 ns) of diphenylmethane, diphenylmethanol, and diarylmethyl halides in acetonitrile and water:alcohol mixtures. A few microseconds after their generation, the radicals were subjected to a laser pulse (20 ns) of 308-nm light. As products of the photolysis of the radicals, the electronically excited radicals, Ar2CH¿* (D1 state), and the corresponding cations, Ar2CH+, were identified. The electronically excited radicals decay with emission of light (¿550 nm in the case of Ph2CH¿*) to their ground state (D0), whereas the cations react with solvent or (other) nucleophiles. The formation of cation from Ar2CH¿ requires two photons (is biphotonic) and proceeds by photoionization of Ar2CH¿*. The photoejected electrons were directly observed in aqueous alcohol. In acetonitrile, the yield of photoionization of Ar2CH¿ (as measured ¿20 ns after the 308-nm pulse) can be increased by the electron scavenger n-butyl chloride, which does not react with Ar2CH¿*. In contrast, CCl4, which does react with Ar2CH¿*, does not lead to an increase in cation yield. © 1993 American Chemical Society.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 7