Abstract: A new electrochemically modulated time resolved uv/vis spectroscopic(EMTRUV/VS) technique based on optical multienannel analyzer (OMA) has been presented. EM-TRUV/VS measurement apparatus consists of five units: an optical signal detection unit which includes a detector, a polychromator, a detector module; an optics unit; a spe-ctroelectrochemical cell unit, which includes optical transparent electrode (OTE); an electrochemical control unit. The limit of time resolution can reach the order of ms by continuously scanning mode and the order of μs by gate mode which is suitable to reversible system with respect to a potential change, respectively. A high S/N ratio can be obtained by subtractive spectrum method. The electrochromism of a poly-o-phenylenediamine (POPD)-coated Au OTE in aqueous 1 mol·L~(-1) H_2SO_4 solution was studied by EMTRUV/VS technique. The optical absorption (λ_(max)=550 nm) of oxidized POPE is ascribed to n→π* transition. The time resolved spectra acquired suggest that the oxidation reaction of PDPD occurs during the first 500 μs and that the electrochromism is controled by H~+ transport.

Key words: Spectroeletrochemistry, Time resolved uv/vis spectroscopy, Poly-ophe-nylenediamine