Photexcitation of Aqueous Ruthenium(II)-tris-(2,2'-bipyridine) with High-Intensity Femtosecond Laser Pulses
The authors report a femtosecond pump-probe study of photochem. of concd. aq. solns. of [Ru(bpy)3]2+, as a function of pump power (up to 2 TW/cm2) at 400 nm excitation. The transient absorption spectra in the 345-660 nm range up to 1 ns time delay enable the observation of the following photoproducts: the triplet 3MLCT (metal-to-ligand-charge-transfer) excited state, the reduced form [Ru(bpy)3]+, the oxidized species [Ru(bpy)3]3+, and the solvated electron eaq. The 3MLCT state is formed within the excitation pulse and undergoes vibrational relaxation in 3-5 ps, as evidenced by the shift of the ligand-centered (LC) absorption band below 400 nm. Even at the highest pump powers, the majority of eaq originates from multiphoton ionization of [RuII(bpy)3]2+ and not from the solvent, generating [RuIII(bpy)3]3+ as a byproduct. At 10 ps time delay, the total concn. of the three product species is balanced by the depleted concn. of [RuII(bpy)3]2+, even at the highest fluences used, indicating that no further reaction products significantly contribute to the overall photochem. On the 100 ps time scale, most probably diffusion-controlled redn. of ground-state [RuII(bpy)3]2+ by solvated electrons occurs, next to recombination between eaq and [RuIII(bpy)3]3+. [on SciFinder (R)]
WOS:000242974300129
2006
110
51
26497
26505
CAN 146:216201
74-1
Radiation Chemistry, Photochemistry, and Photographic and Other Reprographic Processes
Laboratory of Ultrafast Spectroscopy, ISIC, BSP,Ecole Polytechnique Federale de Lausanne,Lausanne-Dorigny,Switz.
Journal
written in English.
18955-01-6 (Tris(2,2'-bipyridine)ruthenium(3+); 56977-24-3 (Tris(2,2'-bipyridine)ruthenium(1+) Role: FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), FORM (Formation, nonpreparative), PROC (Process) (transient absorption study of photochem. of concd. aq. solns. of [Ru(bpy)3]2+ under high-intensity femtosecond laser excitation); 15158-62-0 (Tris(2,2'-bipyridine)ruthenium(2+) Role: PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (transient absorption study of photochem. of concd. aq. solns. of [Ru(bpy)3]2+ under high-intensity femtosecond laser excitation)
REVIEWED
EPFL