Electron Photodetachment from Aqueous Anions. 1. Quantum Yields for Generation of Hydrated Electron by 193 and 248 nm Laser Photoexcitation of Miscellaneous Inorganic Anions

Abstract

Time-resolved transient absorption spectroscopy has been used to determine quantum yields for electron photodetachment in 193 nm and (where possible) 248 nm laser excitation of miscellaneous aqueous anions, including hexacyanoferrate(II), sulfate, halide anions (Cl -, Br -, and I - ), pseudohalide anions (OH -, HS -, and CNS - ), and several common inorganic anions for which no quantum yields have been reported heretofore: SO 3 2-, NO 2 -, NO 3 -, ClO 3 -, and ClO 4 - . Molar extinction coefficients for these anions and photoproducts of electron detachment from these anions at the excitation wavelengths were also determined. These results are discussed in the context of recent ultrafast kinetic studies and compared with the previous data obtained by product analyses. We suggest using electron photodetachment from the aqueous halide and pseudohalide anions as actinometric standards for time-resolved studies of aqueous photosystems in the UV.