In Situ Picosecond XAFS Study of an Excited State of Tungsten Oxide

The electronic state modification and the decay process of WO3 after photoabsorption were followed using picosecond X-ray absorption fine structure (XAFS) spectroscopy. The W d(e(g)) orbital was filled by transition from the oxygen valence state. The decay process is explained mostly by a first-order process with a rate constant k = 0.5 +/- 0.1 ns(-1). The UV optical length is extremely important to follow the photoreduction process using XAFS spectroscopy.