HIGH PRESSURE STUDIES OF J-AGGREGATES
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Date
1996
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Ohio State University
Abstract
The spectral shift of J-bands under high pressure up to 60 kbar has been investigated for J-aggregates of different cyanine dyes. Under conditions where no J-band can be observed at normal pressure, J-aggregates are formed at higher pressure. A red shift of absorption upon increasing pressure was found with a linear dependence of line position on pressure. The results can be explained by a change of dipolar coupling of monomer molecules in the aggregate due to decreasing center-to-center distances. The different pressure slopes of various aggregates are interpreted from their different aggregate structures. The monomer absorption is also red shifted under pressure, but the pressure dependence is quite different and can be described by a solvent shift. From the linear dependence, the dipole-dipole coupling energy J can be determined with a simple theory. The general applicability and limitations of this method are discussed.
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$^{a}$ Current address: Alte Toepferstrasse 14, D-31832 Springe-Voelksen, Germany.
Author Institution: Department of Chemistry, Brandeis University; Fachbereich Physik, Free University
Author Institution: Department of Chemistry, Brandeis University; Fachbereich Physik, Free University