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Author Milder, S. J. ♦ Brunschwig, B. S.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CHEMISTRY ♦ PLATINUM COMPLEXES ♦ FLUORESCENCE ♦ RADICALS ♦ TEMPERATURE DEPENDENCE ♦ ANIONS ♦ TIME RESOLUTION ♦ TEMPERATURE RANGE 0273-0400 K ♦ TEMPERATURE RANGE 0065-0273 K ♦ DEUTERIUM COMPOUNDS
Abstract The lifetime of the picosecond fluorescence of Pt{sub 2}(pop = {mu}-P{sub 2}O{sub 5}H{sub 2}) has been observed to increase with decreasing temperature (e.g., from 40 ps at 290 K to 740 ps at 80 K in H{sub 2}O:glycerol (1:2)). The longer lifetimes at the lower temperatures are attributed to a decrease in the rate of the nonradiative decay of the short-lived emissive state, {sup 1A}{sub 2u}, to the long-lived emissive state, {sup 3}A{sub 2u}, of the complex. The variation of the lifetime of the {sup 1}A{sub 2u} state with temperature has been fit to two-channel expressions that include both a temperature-independent term and a term that is derived from a single-mode quantum treatment of nonradiative decay in either its normal or high-temperature limit. The temperature dependence of the lifetime in each solvent yields sufficient information to define only three parameters, while the two-channel, single-mode quantum term in the high-temperature limit is used ({kappa}{sub obs}= {kappa}{sub o} + (A/{radical}RT) exp(-E{sub a}/RT)), the three independent parameters can be well defined in each solvent. In nondeuterated solvents the decay of the {sup 1}A{sub 2u} state gives values of A that vary from 9.2 x 10{sup 12} to 6.0 x 10{sup 14} s{sup {minus}1}, values of E{sub a} that vary from 890 to 1590 cm{sup {minus}1}, values of {kappa}{sub o} that are almost independent of solvent ((1.5 {plus_minus} 0.2) x 10{sup 9} s{sup {minus}1}), and low-temperature lifetimes that vary from 620 to 850 ps. Upon solvent deuteration, the low-temperature lifetime of the {sup 1}A{sub 2u} state increases to 2170 ps. The temperature-dependent component of the {sup 1}A{sub 2u} decay is attributed to a nonradiative pathway involving strong coupling between the {sup 1}A{sub 2u} and {sup 3}A{sub 2u} states in which the high-energy modes of the solvent are important accepting modes. 53 refs., 6 figs., 4 tab.
ISSN 00223654
Educational Use Research
Learning Resource Type Article
Publisher Date 1992-03-05
Publisher Department Brookhaven National Laboratory (BNL), Upton, NY
Publisher Place United States
Journal Journal of Physical Chemistry
Volume Number 96
Issue Number 5
Organization Brookhaven National Laboratory (BNL), Upton, NY


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