Influence of solute-fluid clustering on the photophysics of pyrene emission in supercritical C{sub 2}H{sub 4} and CF{sub 3}H
- State Univ. of New York, Buffalo, NY (United States)
In this paper, we continue our investigations of the photophysics of pyrene emission in supercritical fluids using steady-state and time-resolved fluorescence spectroscopy. Specifically, we study pyrene photophysics in sub- and supercritical C{sub 2}H{sub 4} and CF{sub 3}H. Steady-state fluorescence is utilized to determine how the local fluid density affects the ground and excited states of pyrene and to probe any potential ground-state dimerization (preassociation). Time-resolved fluorescence provides details of the mechanism of pyrene excimer formulation and the kinetics of solute-solute interactions. The temperature and density dependence of the recovered bimolecular rate constant for pyrene in supercritical C{sub 2}H{sub 4} follows that which had been reported in supercritical CO{sub 2} and liquid solvents, i.e., the excimer formation is diffusion controlled. In supercritical CF{sub 3}H this rate constant is much slower than predicted based on diffusion control arguments. These results indicate that enhanced solute-solvent interactions (clustering) strongly affect the pyrene excimer reaction in CF{sub 3}H. 53 refs., 10 figs., 4 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 568109
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 20 Vol. 114; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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