Journal Article

PUBDB-2022-05333

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Symmetry-resolved CO desorption and oxidation dynamics on O/Ru(0001) probed at the C K-edge by ultrafast x-ray spectroscopy

LaRue, J. (Corresponding author) ; Liu, B. ; Rodrigues, G. L. S. ; Liu, C. ; Garrido Torres, J. A. ; Schreck, S. ; Diesen, E. ; Weston, M. ; Ogasawara, H. ; Perakis, F. ; Dell’Angela, M. ; Capotondi, F. ; Ball, D. ; Carnahan, C. ; Zeri, G. ; Giannessi, L. ; Pedersoli, E. ; Naumenko, D. ; Amann, P. ; Nikolov, I. ; Raimondi, L. ; Spezzani, C. ; Beye, M.XFEL.EU*DESY* ; Voss, J. ; Wang, H.-Y. ; Cavalca, F. ; Gladh, J.Extern* ; Koroidov, S. ; Abild-Pedersen, F. ; Kolb, M. ; Miedema, P. S.Extern*DESY* ; Costantini, R. ; Heinz, T. F. ; Luntz, A. C. ; Pettersson, L. G. M. ; Nilsson, A.

2022
American Institute of Physics Melville, NY

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Please use a persistent id in citations: doi:10.1063/5.0114399  doi:10.3204/PUBDB-2022-05333

Abstract: We report on carbon monoxide desorption and oxidation induced by 400 nm femtosecond laser excitation on the O/Ru(0001) surface probed by time-resolved x-ray absorption spectroscopy (TR-XAS) at the carbon K-edge. The experiments were performed under constant background pressures of CO (6 × 10$^{−8}$ Torr) and O$_2$ (3 × 10$^{−8}$ Torr). Under these conditions, we detect two transient CO species with narrow 2$π^*$ peaks, suggesting little 2π* interaction with the surface. Based on polarization measurements, we find that these two species have opposing orientations: (1) CO favoring a more perpendicular orientation and (2) CO favoring a more parallel orientation with respect to the surface. We also directly detect gas-phase CO2 using a mass spectrometer and observe weak signatures of bent adsorbed CO2 at slightly higher x-ray energies than the 2$π^*$ region. These results are compared to previously reported TR-XAS results at the O K-edge, where the CO background pressure was three times lower (2 × 10$^{−8}$ Torr) while maintaining the same O$_2$ pressure. At the lower CO pressure, in the CO 2$π^*$ region, we observed adsorbed CO and a distribution of OC–O bond lengths close to the CO oxidation transition state, with little indication of gas-like CO. The shift toward “gas-like” CO species may be explained by the higher CO exposure, which blocks O adsorption, decreasing O coverage and increasing CO coverage. These effects decrease the CO desorption barrier through dipole–dipole interaction while simultaneously increasing the CO oxidation barrier.

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Contributing Institute(s):

1. FS-FLASH (FS-FLASH)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. VH-NG-1105 - Novel soft X-ray spectroscopies for materials science (2016_IVF-VH-NG-1105) (2016_IVF-VH-NG-1105)

Experiment(s):

1. Measurement at external facility

Appears in the scientific report 2022

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; Nationallizenz ; PubMed Central ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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