Event
Following the energy transfer between hydrogen atoms and surfaces using scattering experiments| Title of the event | Following the energy transfer between hydrogen atoms and surfaces using scattering experiments |
| Series | MPI Campus Seminar |
| Organizer | Max-Planck-Institut für biophysikalische Chemie (MPIBPC) |
| Speaker | Kerstin Krüger |
| Speaker institution | Department of Dynamics at Surfaces |
| Type of event | Seminar |
| Category | Forschung |
| Registration required | Nein |
| Details | Hydrogen atom scattering from various surfaces under ultra-high vacuum conditions is used to investigate the process of energy transfer during the interaction of impinging atoms with a surface sample, thereby providing information about surface dynamics and important steps in surface reactions, e.g. chemical binding and adsorption. The simplicity of the system makes it particularly interesting for a detailed comparison between high-level experiments and first principle theories. Photolysis of hydrogen halide molecules with ultraviolet or vacuum-ultraviolet photons generates nearly monoenergetic atomic hydrogen beams with translational energies in the range of 0.4 to 7 eV. These hydrogen atoms are scattered from the surface sample, and their translational energy after the collision is probed by the Rydberg-atom time-of-flight method to obtain scattering-angle resolved translational energy loss spectra. For an insulating surface, it was shown that the collisions are nearly elastic, whereas hydrogen atoms colliding with a metal surface possess a large translational energy loss that can be explained by energy transfer to electron-hole pair excitation. [1] In contrast, for hydrogen atoms colliding with epitaxial graphene grown on a platinum (111) substrate, the formation of a transient chemical bond could be observed. Here, the scattering distributions exhibit a bimodal behaviour with a strongly inelastic and a nearly-elastic scattering channel, depending on whether the barrier to chemical bond formation is overcome or not, respectively.[2] In a current project we investigate hydrogen atom scattering from a semiconducting, reconstructed germanium (111) surface. Again, two different scattering channels are observed, potentially arising from nearly-elastic energy transfer and either electronic excitation over the surface band gap or the formation of a transient bond. To further elucidate the experimental findings, comparison with theoretical models will be required. Because of the surface reconstruction, this system represents a particularly challenging, yet very interesting task for theoretical simulations. References: [1] O. Bünermann et al., Science 2015, 350, 1346. [2] H. Jiang et al., Science 2019, 364, 379 |
| Date | Start: 23.06.2021, 11:00 Uhr Ende: 23.06.2021 , 12:00 Uhr |
| Location |
Max-Planck-Institut für biophysikalische Chemie (MPIBPC) (Am Faßberg 11) Online |
| Contact |
05513961108 stefan.gloeggler@mpibpc.mpg.de |