ULTRAFAST X-RAY-ABSORPTION PROBING OF A CHEMICAL-REACTION

Ultrafast x-ray techniques can, in principle, allow us to more directl y watch the time evolution of matter, with atomic spatial resolution a nd with time resolution on the scale of atomic motions such as the mak ing and breaking of chemical bonds, in order to more directly observe the fundamental molecular dynamics underlying the concept of ''mechani sm'' in inorganic, organic, and biochemical reactions. As a step towar d this goal, we have observed a chemical reaction process, photoinduce d dissociation of gas phase SF6 molecules, detected by ultrafast near- edge x-ray absorption spectroscopy with time resolutions of 1.5-3 ps, near the sulfur K edge at a photon energy of 2.48 keV (4.98 A). (C) 19 96 American Institute of Physics.