Reduction of Sm(3+) to Sm(2+) by an intense femtosecond laser pulse in solution.

Samarium 3+ ions in methanol were found to be reduced to the corresponding 2+ ions upon irradiation with intense femtosecond laser pulses. The reduction was observed at both pulses with central wavelengths of 403 nm converted from an 800 fs fundamental pulse and 800 nm with a duration of 43 fs. When the laser wavelength was tuned to the 4f-4f absorption at 403 nm corresponding to the (6)P(3/2) <-- (6)H(5/2) transition, the reduction occurred by multiphoton absorption, presumably due to reaching the deep charge transfer state. In the case of excitation by 800 nm pulses of the fundamental wavelength of the Ti:sapphire laser, the reduction is considered to occur via solvent ionization followed by electron capture by Sm(3+). The product Sm(2+) was detected by its fluorescence, which was observed for the first time in solution and showed a broad spectrum peak around 750 nm with a quantum yield of 0.050 in methanol in the presence of 15-crown-5-ether.