dc.creator Hatch, G. F. en_US dc.creator Nieman, G. C. en_US dc.date.accessioned 2006-06-15T16:40:29Z dc.date.available 2006-06-15T16:40:29Z dc.date.issued 1967 en_US dc.identifier 1967-R-2 en_US dc.identifier.uri http://hdl.handle.net/1811/15330 dc.description Author Institution: Department of Chemistry, University of Rochester en_US dc.description.abstract Triplet-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 dc.format.extent 200040 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title TRIPLET-TRIPLET ANNIHILATION IN ISOTOPIC MIXED CRYSTALS. en_US dc.type article en_US
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