Time-resolved photoelectron spectroscopy for the study of dynamic surface species

The principle and experimental setup of time-resolved photoelectron spectroscopy are outlined. In comparison to conventional molecular beam relaxation spectrometry a reaction channel is analyzed not only at the end but prior to the end. In at least three points time-resolved photoelectron spectroscopy is superior to photoelectron spectroscopic experiments under static and direct current adsorption conditions: (1) a general increase in detection power of transient adsorbates and contaminations; (2) the possibility to discriminate by individual relaxation time between species that cannot be resolved in their binding energy; and (3) a significant simplification of the mathematical formalism in comparison to conventional molecular beam relaxation spectrometry and a more straightforward understanding of the results, in particular the chemical identification of transient species. This is illustrated with time-resolved UV-photoelectron spectra of intermediate adsorbed carbon in the catalytic decomposition of methanol on iron and with time-resolved x-ray photoelectron spectra of intermediate adsorbed oxygen in adsorption and catalysis of methanol/oxygen mixtures on iron.