Multiphoton Reduction of Eu3+ to Eu2+ in Methanol Using Intense, Short Pulses from a Ti:Sapphire Laser

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 103; no. 20; pp. 3910 - 3916
• Main Authors: Nakashima, Nobuaki, Nakamura, Shin-ichi, Sakabe, Shuji, Schillinger, Helmut, Hamanaka, Yasushi, Yamanaka, Chiyoe, Kusaba, Mitsuhiro, Ishihara, Nobuo, Izawa, Yasukazu
• Format: Journal Article
• Language: English
• Published: American Chemical Society 20.05.1999
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp984120t

Multiphoton reduction of Eu3+ to Eu2+ in methanol was induced by irradiation with the second harmonic (394 nm, 2 ps) of a Ti:sapphire laser. The conversion efficiencies were increased to 0.3 for short pulse excitation, as compared to on the order of 10-5 for a nanosecond dye laser pulse. It appears that a three-photon process pumps a deep charge-transfer state from which Eu3+ efficiently dissociates to Eu2+. On the basis of the excitation spectra, the first intermediate state is the 5L6 state, which is one of the f-electronic excited states. The Eu2+ concentration increased shot by shot and approached a plateau. The saturation behavior will be explained in terms of the back photooxidation of Eu2+ to Eu3+.