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In order to develop polypeptide-based second order nonlinear optical materials, we have derivatized succinylated poly(l-lysine) with a spiropyran. Spin coated thin films(2i thickness) of this material on indium tin oxide-coated glass were corona-poled(6 x iO V/rn) under conditions of variable temperature. The degree of alignment and nonlinear optical properties were monitored by measurement of the intensity of second harmonic signal resulting from irradiation at 1064 nrn. The dark-adapted polypeptide was in the spiropyran form. The second harmonic signal intensity was 20 times greater than that of the dark-adapted sample. The results demonstrate the feasibility of development of a light-activated nonlinear optical material.

This article presents the experimental photodischarge kinetics of electrostatically fatigued dual-layer organic photoconductors characterized by an electrophotographic incremental charging technique that reveals the differences in the photoconductor charging profiles. During normal operation, 15% of the holes that migrate to the surface after photodischarge are not neutralized by the negative surface ions. The accumulation of these lingering surface charges (charge transport material radical cations) manifests itself as defects in half-tone images, as either missing or reduced size dots or lines. In the presence of corona gases, these surface holes oxidize and reduce the energy barrier for hole injection from a positively charged surface, e.g., contact with a transfer roller. These injected holes accumulate near the charge generation layer and require twice the amount of negative charge to attain the same surface potential as that of a new organic photoconductor (OPC) drum. The damaged depth of this injection region extends to about 50 nm into the OPC surface and is easily removed by the printer's abrasion mechanisms (e.g., cleaning blade, toner, paper). d

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