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56
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85034925064
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-
As pointed out to us by H. Sillescu, this statement needs to be qualified when bleaching is at least partially selective, since more mobile probes disproportionately influence the observed anisotropy For the experiments reported here, this effect is minor. Calculations indicate that the [formula omitted] observed at various bleach depths is 15%–35% shorter than the true [formula omitted] which characterizes the distribution of relaxation times for the remaining tetracene molecules. The β value observed at 244.5 K is apparently not distorted by selective bleaching, since the same β was observed at 250 K where no selective bleach occurs
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-
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57
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85034919014
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-
At [formula omitted] the anisotropy written with the deep bleach has decayed to approximately [formula omitted] of its initial value. The value of [formula omitted] we obtain will be characteristic of the dynamics at this time
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-
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-
60
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-
85034922881
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-
The contribution of spatially heterogeneous dynamics to the distribution of relaxation times can also be estimated from the increase in β from 0.62 to about 0.68 after a 60% bleach; this bleach narrows the distribution by about 40%, indicating that spatially heterogeneous dynamics account for at least this fraction of the nonexponential behavior. This is a lower bound both because bleaching is not likely to be perfectly selective and because an even larger increase in β would be expected for a deeper bleach. This result is consistent with the result given in the text but is not as reliable due to errors associated with measuring small changes in β
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61
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85034919258
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-
Near [formula omitted] β values for tetracene in OTP ([formula omitted]) and OTP in OTP [[formula omitted] sec Ref. 1(c)] are different. The discussion in this section refers directly to the distribution of relaxation times for tetracene rotation. The differences in the β values may be related to the different shapes of the molecules, differences in which vectors contribute to the correlation functions measured by optical and NMR experiments, or the influence of internal motion in OTP
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62
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-
85034929863
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-
This assumption may seem inconsistent with the known results that this relationship breaks down over large length scales at low temperatures (see Refs. 17 and 18). It is possible that the existence of spatial heterogeneity can explain this break down on large length scales without any change in the local relationship between translation and rotation (see Refs. 28, 56, and 57)
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63
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85034917076
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-
Usingthis assumption, the slow decay of Fig. 6 is reasonable. Since some local reorientation times are longer than [formula omitted] the function in Fig. 6 should not decay to zero until more than [formula omitted]
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75
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85034926903
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-
Ph.D thesis, University of Wisconsin, Madison, Wisconsin
-
(1994)
, pp. 165
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Cicerone, M.T.1
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