Electroabsorption in disordered solids. II. Anthracene crystals and thin films

Abstract

For pt.I see ibid., vol.7, p.1595 (1974). Electroabsorption data are presented for anthracene in its crystalline and disordered forms. Particular emphasis is placed on the role of the substrate temperature Ts in determining the structure of vacuum-deposited films. For substrate temperatures below the optimum temperature for surface quality (T0=-60 degrees C) two electroabsorption peaks are observed; the one at 396 nm is thought to be associated with anthracene molecules in a crystalline arrangement. However, the other at 405 nm is attributed either to a disordered phase or more probably to diffraction effects produced by orientational randomness of the anthracene crystallites. The magnitude of both peaks vary with the square of the electric field (quadratic Stark effect). The magnitude of the higher-wavelength peak reduces rapidly and monotonically as Ts reaches the region of T0.