A Raman Spectroscopic and Electrochemical Study on Photoinduced Crystal Growth of DABCO (Triethylenediamine) Polyiodide Upon a Silver Electrode

Surface Raman spectra of a silver electrode contacting with an acidic solution containing triethylenediamine (DABCO) and sodium iodide showed some new Raman peaks, which were neither the peaks of dissolved DABCO species nor of iodide. These were ascribed to diprotonated DABCO polyiodide crystal, formed and attached onto the laser-irradiated site of the silver electrode. Several facts implied that laser illumination used for the Raman measurement promoted the growth of the crystal; the possibility of photoinduced electrochemical crystal formation was suggested. The mechanisms for this local crystal growth of diprotonated DABCO polyiodide on the silver electrode was examined, as to its dependence upon the solution composition and applied potential. Keywords: Laser-induced crystal growth.