The understanding of ultrafast (femtosecond) dynamics of surface processes such as chemical reactions is essential for an integral understanding of catalysis. Crucial questions concerning the dynamics are: What are the typical time scales on which energy transfer (e.g. between adsorbate and substrate) occurs at the surface? What are typical reaction times and what are the reaction intermediates and transition states, and their lifetimes? We intend to answer these questions by taking spectroscopic "snapshots" of the surface every few femtoseconds as a surface reaction proceeds: such a reaction can be initiated by a powerful excitation pulse, and its temporal evolution is followed using a second, interrogating femtosecond (probe) pulse, which can be variably delayed with respect to the pump pulse. With the results of this project, novel and fundamental insights into important surface processes will be obtained, that cannot be obtained by any other experimental means. These insights are significant not only from a fundamental point of view, but have great potential impact on fields such as catalysis, electrochemistry and semi-conductor technology. They are complementary to those obtained in the molecular beam and photochemical surface science experiments in the group of Prof. Kleyn. The planning looks as follows: First year: Purchase, construction and installation of optical components for the time-resolved surface experiments; initiation of collaboration with the group of Dr. H.J. Bakker for the generation of intense IR pulses; reconstruction of existing ultra-high vacuum (UHV) system, installation and cleaning of Ru crystal. Second year: Initial test experiments on surfaces outside UHV (on e.g. self-assembled monolayers); characterisation of photochemical pathways of investigated systems by post-irradation and mass spectrometric techniques; integration of optical and UHV systems: time-resolved optical experiments inside UHV. Third year: Time-resolved optical pump-probe experiments inside UHV.