Anomalously high efficiencies for electronic energy transfer from saturated to aromatic hydrocarbons at low aromatic concentrations
- Univ. of Minnesota, Minneapolis (United States)
The absolute efficiency of electric energy transfer from cis-decalin excited at 161 nm to 2,5-diphenyloxazole (PPO) has been measured over a PPO concentration range from 1.0 [times] 10[sup [minus]2] to 2.0 [times] 10[sup [minus]5] M via measurements of both the cis-decalin and the PPO fluorescence. At concentrations above ca. 10[sup [minus]3] M, the normal fluorescing state of cis-decalin plays the dominant role in the energy transfer. At lower concentrations, however, there appears to be an important contribution from some other nonfluorescing state of cis-decalin. The fraction of PPO fluorescence generated by this dark state rises from ca.10% at 0.01 M to ca. 70% at 2 [times] 10[sup [minus]5] M. The effects of addition of O[sub 2] of dilution with isooctane, and of cooling to [minus]35[degrees]C on the quantum yield of this process are reported. The results obtained here confirm earlier results with other saturated hydrocarbon donor + aromatic acceptor systems that have suggested the existence of a dark donor state that dominates the transfer process at low acceptor concentrations via some anomalously efficient mechanism. For the system cis-decalin + PPO at 21[degrees]C, the transfer probability for this process at the lowest concentration studied of 2 [times] 10[sup [minus]5] M is 2.5 [times] 10[sup [minus]3] per photon absorbed and 0.060 per dark state produced. 34 refs., 13 figs., 6 tabs.
- OSTI ID:
- 6486424
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 97:2; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DECALIN
ENERGY TRANSFER
OXAZOLES
CONCENTRATION RATIO
EFFICIENCY
FLUORESCENCE SPECTROSCOPY
PROBABILITY
ALKANES
AZOLES
CYCLOALKANES
EMISSION SPECTROSCOPY
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
SPECTROSCOPY
400500* - Photochemistry