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dc.creatorHatch, G. F.en_US
dc.creatorNieman, G. C.en_US
dc.descriptionAuthor Institution: Department of Chemistry, University of Rochesteren_US
dc.description.abstractTriplet-triplet annihilation in dilute mixed crystals of benzene containing $C_{6}H_{6}$ or $1,3,5-C_{6}H_{3}D_{3}(\sim 0.2%)$ dissolved in $C_{6}D_{6}$ has been studied in detail as a function of temperature from $2^{\circ}$ to $15^{\circ}K$. Measurements have been made of the build up and decay kinetics as well as the steady-state intensities of phosphorescence and delayed fluorescence as a function of time, temperature, excitation intensity and wavelength, and guest concentration and trap depth. All observations on the two-component systems can be adequately explained on the basis of the following rate law: $\frac{d[T]}{dt} = R_{o}c - (k_{1} + R_{o})[T] - k_{2}[T]^{2}.$ Here [T] is the triplet state population, $k_{1}$ and $k_{2}$ are respectively the first- and second-order decay constants, $R_{o}$ is a factor proportional to the excitation intensity, and c is the guest concentration. Computer analysis of the phosphorescence decay as the sum of first- and second-order processes and measurements of the steady-state phosphorescence intensity as a function of temperature yield independent measurements of the first- and second-order rate constants. The second-order annihilation rates calculated by both methods agree very well and imply both a temperature activated and a large (20%) temperature independent annihilation process. It is both predicted and observed that with increasing the temperature from $8^{\circ}$ to $12^{\circ}K$ in these ultrapure crystals, the first-order decay constant increases by less than a factor of two while the second-order annihilation constant increases by five or more orders of magnitude!en_US
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dc.publisherOhio State Universityen_US

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