Electronic and Molecular Structure of Photoexcited [RuII(bpy)3]2+ Probed by Picosecond X-ray Absorption Spectroscopy

L2,3 x-ray absorption spectra of aq. [RuII(bpy)3]2+ were recorded in its ground and excited states, 50 ps after short pulse laser excitation. Significant changes in both the XANES (x-ray Near-Edge Absorption Structure) and the EXAFS (Extended x-ray Absorption Fine Structure) regions of the excited state complex are detected. The XANES line shapes were quant. simulated using a crystal field multiplet code in trigonal symmetry. Spectral changes in the EXAFS region of both ground and excited states are analyzed to ext. structural parameters of their corresponding mol. structures. A Ru-N bond contraction by .apprx.0.03 .ANG. in the excited-state complex, as compared to the ground-state compd., was obtained. This contraction results from electrostatic and polarization contributions, limited by steric constraints on the bpy ligands. [on SciFinder (R)]