ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The photobleaching process has been studied systematically in poly(methylphenylsilane) thin films with thickness comparable to or less than the penetration depth of incident ultraviolet light. It is found out that the photoscission of σ bonds proceeds from longer segments of Si chains to shorter segments, which has been overlooked in an analysis of the photobleaching process so far. Taking into account this phenomenon and its temperature dependence, a thermally assisted photoscission model is proposed. In the model the activation energy cursive-epsilon has a distribution combining two exponential functions of exp(cursive-epsilon/cursive-epsilon1) in a low energy region and exp(−cursive-epsilon/cursive-epsilon2) in a high energy region with the transition energy cursive-epsilonT separating the two. The shape of the energy distribution is independent of the length of segments and the photoscission cross section Cr is larger for longer segments. The analysis based on this model is fairly consistent with the experimental results. The parameters of cursive-epsilon1, cursive-epsilon2, cursive-epsilonT and Cr are confirmed to be 38 meV, 31 meV, 73 meV, and 5.0×10−17–1.3×10−16 cm2, respectively. The photodegradation of the photoluminescence from the thin films is also well explained on the basis of the proposed model. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.370802
