Photoelectric evidence for a neutral excited state in fully polymerized polydiacetylene-p-(toluenesulfonate) single crystals
✍ Scribed by B. Reimer; H. Bässler
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- English
- Weight
- 332 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The intensity dependence of photocurrent transients excited by the 1.06 JI line of a Nd laser bas been measured. Observation of an 12 and an 1' branch indïcate that charge carriers can be generated via twoquantum absorption and that at high intensities photoionïzation of a neutral excited state with a lïfetime of the order 10-r" s dominates.
Based on theoretical arguments
[ 11 it has been suggested that the streng optical absorption observed witb certain polydiacetylenes near 2 eV originates from a transition between valence and conduction band of the polymer chain. This assignment bas been supported by an analysís of the absorption band profile [2] although it is known from the literature that absorption lines resulting from an exciton transition can also be asymmetrie [3] _ Stationary photoconductivity measurements, on the other hand, have demonstrated that the number of charge carrier pairs generated per absorbed photon is only 10-4 or less [4] _