HIGHER YIELD OF PHOTOREDUCTION FROM EU3+ TO EU2+ WITH SHORTER WAVELENGTH IRRADIATION

We have found that the photoreduction yield from Eu3+ to Eu2+ depends on excitation wavelength within a single charge-transfer band. The quantum-yields phi were 0.12+/-0.02 (at 193 nm) and 0.06+/-0.01 (at 222 nm) in aqueous solution. and 0.42+/-0.07 (at 222 nm ) and 0.35+/-0.06 (at 248 nm) in methanol solution, The escape probability of Eu2+ from the photochemically prepared geminate pair is suggested to be higher with shorter-wavelength excitation.