Direct observation of surface chemistry using ultrafast soft-x-ray pulses - art. no. 025501

We present the first demonstration of the use of ultrafast extreme-ultravio let pulses to directly monitor a surface chemical reaction on femtosecond t ime scales. By adsorbing molecular oxygen onto a platinum surface and excit ing it with an ultrafast laser pulse, changes in the oxygen-platinum chemic al bond on a subpicosecond time scale were observed through changes in the photoelectron spectra. This work demonstrates a powerful new technique for studying reactions of interest in catalysis and for probing changes of loca l order on surfaces on their fundamental time scales.