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The radiolytic production of CdS particles from solutions containing cadmium ions and a thiol (3-mercapto-1,2-propanediol, RSH) is described. The production of the colloids is initiated by the reaction of solvated electron with the thiol to release HS" ions. The polynuclear complexes of cadmium with the thiolate form of RSH act as moderators to the growth of the particles and allow reproducible production of practically any predetermined size particles. The complexes at the surface of the particles also stabilize the particles for long periods of time. The particles are strongly fluorescent from size of ca. 8 Á in radius. Excess electrons in these particles lead to bleaching of the exciton band due to Coulomb screening effects. At higher doses, formation of cadmium atoms leads to increased absorption in the visible range.

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Optical effects due to size quantization in three dimensions have been observed for CdS and PbS colloids with particle diameters less than 50 8, and 20 to 200 A, respectively. The optical absorption edge is blue shifted -0.9 eV for the CdS colloid; for PbS colloids the shift is -2 eV for particle diameters 20-30 A, and -1 eV for particle diameters 50-200 A. The results are consistent with perturbation of the semiconductor band structure due to carrier confinement resulting in an increase in the effective band gap, pictures of the colloids, Ken Marsh and John Connolly for obtaining emission spectra, and Brad Thacker for technical assistance in several experiments. A.J.It is shown that the SI state of 1H-indazole in acetic acid undergoes double proton transfer along the hydrogen bonds in the indazole-acetic acid complex. The proton transfer converts 1H-indazole into 2H-indazole. The rate of proton transfer is estimated to be 2.7 X lo9 s-I from transient fluorescence measurements.