Direct, Real-Time Measurements of Adsorption and Desorption Kinetics Using Time-Resolved Electron Energy Loss Spectroscopy

Recent instrumental improvements in high resolution electron energy loss spectroscopy (EELS) make possible the recording of complete vibrational spectra on the millisecond time scale. We use this improved time resolution to measure directly adsorption and desorption process on surfaces in real-time. Specifically, we follow both the adsorption kinetics (reactive sticking probability) and the orientation of formic acid on Cu(100) as a function of surface temperature. In a second example, we measure the mean residence time (and therby the desorption kinetics) of carbon monoxide also on Cu(100) using a combination of time-resolved EELS and a pulsed molecular beam source.