Ionic photodissociation of excited electron donor-acceptor systems. I. An empirical equation on the relationship between the yield and the solvent dielectric constant

Hiroshi Masuhara*, Tetsuro Hino, Noboru Mataga

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

117 Scopus citations

Abstract

Ionic photodissociation yields of some 1,2,4,5-tetracyanobenzene complexes and of the pyrene-N,-N-di-methylaniline exciplex system in various solvents were obtained by using the nanosecond laser photolysis method. On the basis of the results obtained, a new empirical equation representing the relationship between the yield and the solvent dielectric constant was proposed, which was discussed from the viewpoints of three different theories: (i) Horiuchi-Polanyi's relation for the activation energy; (ii) Onsager's ion recombination model; and (iii) phenomenological theory of reaction rates based on Pick's law. With i and ii the empirical rule was verified qualitatively but not with iii, which seems to mean that the ions produced begin to diffuse with excess energy from the excited state nonrelaxed with regard to solvent orientation. The correlation of the rate constant of dissociation with various solvent polarity parameters was also examined. The solvent effect on ionic photodissociation seems to be well explained in terms of dielectric constant.

Original languageEnglish
Pages (from-to)994-1000
Number of pages7
JournalJournal of Physical Chemistry
Volume79
Issue number10
DOIs
StatePublished - 1 May 1975

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