The kinetics of the electrodeposition of CdTe from an aqueous solution containing CdSO,, TeO, and HzS04 were investigated by using a rotating ring-disc electrode. The results for tellurium deposition alone indicated that the reaction occurs through a six-electron reduction of HTeOz+ to H,Te, followed by a reaction between H,Te and HTe02+ yielding tellurium. At HTeOZ+ concentrations greater than M, the second step of this process is very fast and the overall reaction behaves as a four-electron reduction of HTeO, + to Te: only at lower HTeOz+ concentrations was evidence observed for the six-electron reduction. The electrodeposition of CdTe occurs through two possible pathways: CdZ+ ions can react with HzTe produced during the reduction of HTeOZ+ and thus yield CdTe, or tellurium deposited on the electrode can react with CdZ+ to yield CdTe. The two reactions compete with the deposition of pure tellurium. Conditions to deposit stoichiometric CdTe are suggested.

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Charge-transfer spectroscopy was used to determine the ionization energies of ten phenothiazine tranquillizers and similar molecules which are stimulants, in order to throw light on the proposed relation between physiological action and electron-donating power, and to compare the ionization energies of the phenothiazines with molecular orbital calculations. All the ionization energies obtained lie in the range 7.0-8.4 eV. The phenothiazines are thus strong electron donors, in agreement with calculations. There is little difference in ionization energies and equilibrium constants of complex formation between tranquillizers and either non-tranquillizers or stimulants. The difference in physiological action of the drugs therefore cannot be dependent on electron-donating power alone.

This paper describes the photovoltaic properties of glass/Au/MgPc/Al cells. High quantum yields were obtained with an applied voltage and moderate yields at short circuit. No evidence of a Schottky barrier or p-n junction was observed.

The band gap, EG, of an organic solid can be estimated by adding the magnitudes of oxidation and reduction potentials of the compound in solution, plus a correction to the ion solvation energy which allows for the different dielectric constants of solvent and solid. Values of EG for 30 organic solids have been estimated. ��� The auto-ionization model, previously used for aromatic hydrocarbons, is applied to dyes and chlorophylls. The values of EG are used to interpret various existing results on photoconduction and semiconduction in dyes and chlorophylls.

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Current-voltage curves in the saturation region of hole injection from aqueous Ce(SO4)2, KI3, and SnCl4 solutions into anthracene are reported. These, and some curves for similar systems appearing in the literature, contrast with the prediction of a flat saturation region from the theory developed by Mehl and Hale. They are inter- preted in terms of field assisted emission from the surface into the bulk of the crystal, although in some systems, particularly Ce(SO4), 1 anthracene, two mechanisms appear to operate. In an Appendix the effects of space charge on the shape of the saturation curve are shown to be small, except near the saturation point in some cases.

Photovoltaic measurements were made on vacuum-evaporated tetracene films sandwiched between an aluminium and a gold electrode. For polychromatic illumination in air open-circuit voltages of up to 1.2 V were observed with the gold electrode positive. The best power conversion efficiency was better than 10-4%. Two modes of carrier production were distinguished, the first resulting from photon absorption in the first tetracene singlet-singlet electronic transition, and the second associated with lower energy red light photons. ��� Persistent voltages were also found to be generated in the dark, the magnitudes of both these and the photovoltages being reversibly increased by the presence of air.