Recent experimental and theoretical developments in time-resolved X-ray spectroscopies

Capturing the evolving geometric and electronic structure in the course of a chemical reaction or biological process is the principal aim of time-resolved X-ray spectroscopies. Recent technological and methodological improvements, such as high repetition rate lasers and femtosecond laser-electron slicing have made this a reality. The advent of X-ray free electron lasers introduces a paradigm shift in terms of the temporal resolution of X-ray spectroscopies, and offer exciting possibilities for time-resolved second-order X-ray spectroscopies and non-linear X-ray experiments. In parallel, the improved data quality is making it increasingly important to accurately simulate the fine spectroscopic details. This has been the driving force for new theoretical methods permitting a detailed interpretation of the spectra in terms of the geometrical and electronic properties of the system. In this contribution, we discuss recent experimental and theoretical developments in ultrafast X-ray absorption spectroscopies (XAS) and explore the new opportunities they offer. (C) 2014 Elsevier B.V. All rights reserved.