Seminars Archive

Observing transient electronic and molecular structures in liquids by picosecond x-ray absorption spectroscopy

Abstract
The importance of capturing the dynamics of molecular motion in real-time is crucial for our understanding of physical, chemical and biological phenomena. In addition, structural changes in molecular systems follow ultrafast electronic structure changes. Therefore, observing both in a given system can provide much deeper insight into its dynamics. Ultrafast optical spectroscopy does not deliver molecular structure. The ideals structural tools are x-rays, via methods such as diffraction or spectroscopy. Here, we will present our recent results on the probing of structural changes in electronically excited solvated species, using picosecond x-ray absorption spectroscopy, in a laser pump/x-ray probe configuration. We will demonstrate the power of this new approach on three different types of processes: intramolecular electron transfer, ultrafast molecular magnetism and solvation dynamics around an atomic ion, and discuss future extensions to biological systems. We will also discuss the future of x-ray absorption spectroscopy, in relation to the development of XFELs. W. Gawelda, M. Johnson, F. M.F. de Groot, R. Abela, Ch. Bressler and M. Chergui, Journal of the American Chemical Society 128 (2006) 5001-5009