Abstract
We describe a model for the treatment of the adsorption-desorption kinetics on a substrate containing reversibly adsorbing sinks (surface steps). This model includes adsorption and desorption onto/from normal and sinks sites, and surface migration between those two types of site. Two different sets of analytical expressions, directly applicable to modulated molecular beam experiments, are presented. The first one gives the amplitude attenuation and the phase-shift of the first harmonic of the desorbed beam. The second one gives an effective relaxation time, obtained by integration of the temporal waveform of the desorbed pulses. By suitable variation of the modulation frequency and the substrate temperature, one can separately measure the desorption energies from the homogeneous substrate and from the sinks, and the activation energy for surface diffusion. This model is applied to modulated molecular beam measurements onto two different systems: new results on the adsorption of Cd on NaCl(100) and results of Lin and Somorjai [Surface Sci. 107 (1981) 573] on the chemisorption of NO on Pt(557) and Pt(111). In both cases, the kinetic parameters of the elementary processes are obtained.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
