Speaker
Description
Surface Action Spectroscopy (SAS) is a method derived from the messenger action spectroscopy typically applied to aggregates in the gas phase to elucidate their structure. To this end, weakly bound atoms, or molecules, the ‘messengers’, are attached to the aggregates as indicators of a vibrational excitation. They may desorb when a vibrational mode is excited with infrared light, which usually stems from a free-electron laser (FEL). The approach permits to record vibrational spectra, which are a fingerprint of the surface structure - comparison with simulated vibrational spectra may reveal it. The same approach can be applied to thin film or single crystal surface structures. We have performed studies of the surface structure of Co
A further activity was the structural characterization of Ni and Au single atoms on Fe
A technical step forward was the implementation of He as a messenger gas, which requires sample temperatures below 2K. This was achieved by an improved shielding of the transferable sample holder against thermal infrared radiation and precooling of the wires to the sample holder as well as a thorough improvement of the thermal heat transfer between the sample and the cryostat. Still, a careful setup of the sample holder is required, but standard commercial transferable sample holder plates suffice.
Presently, the structure of a Ni-N-C model catalyst based on an epitaxial graphite film is investigated, aiming to gain insight into structure-reactivity relationships for the carbon dioxide electrocatalytic reduction. Continuation of the successful single atom catalyst structure studies will be another direction for future studies.
References
[1] Liu, Y, Y. Peng, M. Naschitzki, S. Gewinner, W. Schöllkopf, H. Kuhlenbeck, R. Pentcheva, B. Roldan Cuenya: Surface oxygen Vacancies on Reduced Co
[2] Liu, Y., Z. Han, S. Gewinner, W. Schöllkopf, S.V. Levchenko, H. Kuhlenbeck, B. Roldan Cuenya: Adatom bonding sites in a Ni-Fe
Abstract Number (department-wise) | ISC 14 |
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Department | ISC (Roldán) |