Research objectives and content
The recent advent of pulsed laser sources allows for the real-time investigation of reaction dynamics: The rate of product formation can be investigated and short-lived reaction intermediates can be observed. Well-defined single crystal metal surfaces in vacuum are widely investigated as model systems for metal-catalyzed reactions. However, investigations concerning the (reaction) dynamics of these systems are lagging. We propose to investigate and control the reaction dynamics at single crystal surfaces by resonant vibrational excitation of adsorbates with ultrashort (femtosecond) infrared pulses, where the vibrational coordinate that is excited lies along, or is strongly coupled to, the reaction coordinate. In these surface pump-probe experiments, a visible probe pulse of femtosecond duration, inducing photo-chemistry, can be variably delayed with respect to the infrared excitation (pump) pulse. Subsequently, desorbed reaction products can be monitored as a function of pump-probe time delay with a mass spectrometer, or the time-evolution of the surface IR absorption spectrum can be determined with sum frequency generation (SFG).
Training content (objective, benefit and expected impact)
These experiments will provide novel, detailed insights in energy flow mechanisms and pathways at surfaces, as well as important insights in the coupling between adsorbate and substrate. This type of knowledge is essential for a fundamental understanding of -industrially very important| metal-catalyzed reactions.