Electronic and molecular structure of photoexcited [Ru(II)(bpy)3]2+ probed by picosecond X-ray absorption spectroscopy

Wojciech Gawelda; Melanie Johnson; Frank M F de Groot; Rafael Abela; Christian Bressler; Majed Chergui

doi:10.1021/ja054932k

Electronic and molecular structure of photoexcited [Ru(II)(bpy)3]2+ probed by picosecond X-ray absorption spectroscopy

J Am Chem Soc. 2006 Apr 19;128(15):5001-9. doi: 10.1021/ja054932k.

Authors

Wojciech Gawelda¹, Melanie Johnson, Frank M F de Groot, Rafael Abela, Christian Bressler, Majed Chergui

Affiliation

¹ Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, Institut des Sciences et Ingénierie Chimiques, CH-1015 Lausanne-Dorigny, Switzerland.

PMID: 16608334
DOI: 10.1021/ja054932k

Abstract

L(2,3) X-ray absorption spectra of aqueous [Ru(II)(bpy)3]2+ have been 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 have been quantitatively simulated using a crystal field multiplet code in trigonal symmetry. In addition, spectral changes in the EXAFS region of both ground and excited states are analyzed in order to extract structural parameters of their corresponding molecular structures. We obtain a Ru-N bond contraction by approximately 0.03 angstroms in the excited-state complex, as compared to the ground-state compound. This contraction results from electrostatic and polarization contributions, limited by steric constraints on the bpy ligands.