Deuterium effect on the quenching of aromatic hydrocarbon triplet excited states by oxygen

Robert Benson, Nicholas Geacintov

Research output: Contribution to journalArticle

Abstract

By using ultraviolet light flash excitation, the triplet (phosphorescence) decay time T of a series of protonated (p) and deuterated (d) aromatic hydrocarbons dissolved in a fluffy freeze-dried polystyrene matrix was studied as a function of oxygen pressure [O 2] at 298°K. The quenching constants y were calculated from linear plots of T~' as a function of [O 2] and the ratios of y(p)/y(d) are 1.2+0.1 for anthracene and 1,2-benzanthracene, 1.9+0.2 for pyrene, 1.4 +0.2 for chrysene, and 2.5+0.4 for naphthalene. These results are interpreted in terms of Franck-Condon factors and the energy transfer quenching model proposed by Kawaoka, Khan, and Kearns in which the'Ag and !£-4 excited states of oxygen are generated, and in which the remaining energy is dissipated by the vibrational modes of the quenched aromatic molecules. In pyrene and in naphtalene, the ' Ag pathway appears to be more important than in chrysene and dominates over the 'Z, mechanism. No conclusions can be reached about the preferred mode of energy transfer to oxygen in anthracene and 1,2-benzanthracene.

Original languageEnglish (US)
Pages (from-to)3251-3257
Number of pages7
JournalThe Journal of chemical physics
Volume60
Issue number8
StatePublished - 1974

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Aromatic Hydrocarbons
Deuterium
Excited states
deuterium
Quenching
hydrocarbons
quenching
pyrenes
Oxygen
anthracene
Energy transfer
oxygen
energy transfer
excitation
Phosphorescence
Polystyrenes
phosphorescence
naphthalene
ultraviolet radiation
flash

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Deuterium effect on the quenching of aromatic hydrocarbon triplet excited states by oxygen. / Benson, Robert; Geacintov, Nicholas.

In: The Journal of chemical physics, Vol. 60, No. 8, 1974, p. 3251-3257.

Research output: Contribution to journalArticle

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