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

Abstract

Multiphoton reduction of Eu 3+ to Eu 2+ 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 Eu 3+ efficiently dissociates to Eu 2+ . On the basis of the excitation spectra, the first intermediate state is the 5 L 6 state, which is one of the f-electronic excited states. The Eu 2+ concentration increased shot by shot and approached a plateau. The saturation behavior will be explained in terms of the back photooxidation of Eu 2+ to Eu 3+ .

Reduction of Yb(III) to Yb(II) by Two-Color Two-Photon Excitation

“…Analyses of the two-photon chemistry might not be simple because of the lack of clear information regarding the lifetimes of the intermediate states. 9,10 (iii) A conventional nanosecond laser photolysis method has been successfully applied to the Yb 3+ system, because the 4f* has a relatively long lifetime of 0.2 μs in EtOH. We measured the spectrum of CT ← 4f* using an IR (976-nm) pulse as an excitation light source.…”

Photo-reduction behavior of sol–gel derived silica materials doped with europium(III) crown ether complex

“…A series of experimental results allow us to propose the photo-reduction mechanism of Eu 3+ ions of the SiO 2 :[Eu(15C5)] 3+ composite materials as follows: at first, the electron in the ground state of Eu 3+ ion is excited to the charge transfer band by UV light irradiation [15]. This excited Eu 3+ ion receives one electron of the unshared electron pairs from the O atom of neighboring silanol group, so that the reduction from Eu 3+ to Eu 2+ ion takes place.…”

Photoluminescent changes of Eu3+ in ZnO–SiO2 glasses induced by femtosecond laser

“…In addition, Eu 3+ ions are hypersensitive to local environments and microstructures and can be used as fluorescent probe. But the reports of luminescent properties of Eu 3+ ions induced by fs laser were very rare [9][10]. Our group reported that hole burning efficiency of Eu 3+ in sol-gel aluminosilicate glasses was increased due to fs laser irradiation [11].…”