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Proceedings Paper

Photophysics And Spectroscopy Of Surface Adlayers: Pyrene On Al2O3(1120)
Author(s): N J Tro; D R Haynes; A M Nishimura; S M George
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Paper Abstract

Electronic absorption and laser-induced fluorescence spectroscopy were used to examine pyrene adsorbed on Al203(1120) in UHV as a function of surface coverage and adlayer order. The absorption maximum of the So->S2 transition shifted from λ = 337 nm at θ = 0.13 ML to λ = 349 nm at θ ≥ 3.0 ML. The observed frequency shifts were explained in terms of dispersion interactions that stabilize the energy of the excited state due to the polarization of the surrounding dielectric. The fluorescence spectrum at 21 K exhibited both monomer and excimer emission. The relative amount of excimer emission increased as the coverage was increased from θ = 0.30 ML to θ = 4.5 ML. Likewise, the fluorescence spectrum was temperature-dependent between 21 and 150 K. As the temperature was increased, the monomer fluorescence intensity decreased while the excimer fluorescence intensity increased. This temperature dependence, together with xenon overlayer studies, suggested that the excimer formation was dependent on pyrene surface mobility. Absorption and fluorescence measurements also indicated that the pyrene adlayer crystallized on the Al203(1120) surface when the adlayer was annealed above 230 K.

Paper Details

Date Published: 15 August 1989
PDF: 13 pages
Proc. SPIE 1056, Photochemistry in Thin Films, (15 August 1989); doi: 10.1117/12.951631
Show Author Affiliations
N J Tro, Stanford University (United States)
D R Haynes, Stanford University (United States)
A M Nishimura, Stanford University (United States)
S M George, Stanford University (United States)

Published in SPIE Proceedings Vol. 1056:
Photochemistry in Thin Films
Thomas F. George, Editor(s)

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