TY  - JOUR
AU  - LaRue, Jerry
AU  - Liu, Boyang
AU  - Rodrigues, Gabriel L. S.
AU  - Liu, Chang
AU  - Garrido Torres, Jose Antonio
AU  - Schreck, Simon
AU  - Diesen, Elias
AU  - Weston, Matthew
AU  - Ogasawara, Hirohito
AU  - Perakis, Fivos
AU  - Dell’Angela, Martina
AU  - Capotondi, Flavio
AU  - Ball, Devon
AU  - Carnahan, Conner
AU  - Zeri, Gary
AU  - Giannessi, Luca
AU  - Pedersoli, Emanuele
AU  - Naumenko, Denys
AU  - Amann, Peter
AU  - Nikolov, Ivaylo
AU  - Raimondi, Lorenzo
AU  - Spezzani, Carlo
AU  - Beye, Martin
AU  - Voss, Johannes
AU  - Wang, Hsin-Yi
AU  - Cavalca, Filippo
AU  - Gladh, Jörgen
AU  - Koroidov, Sergey
AU  - Abild-Pedersen, Frank
AU  - Kolb, Manuel
AU  - Miedema, Piter S.
AU  - Costantini, Roberto
AU  - Heinz, Tony F.
AU  - Luntz, Alan C.
AU  - Pettersson, Lars G. M.
AU  - Nilsson, Anders
TI  - Symmetry-resolved CO desorption and oxidation dynamics on O/Ru(0001) probed at the C K-edge by ultrafast x-ray spectroscopy
JO  - The journal of chemical physics
VL  - 157
IS  - 16
SN  - 0021-9606
CY  - Melville, NY
PB  - American Institute of Physics
M1  - PUBDB-2022-05333
SP  - 164705 
PY  - 2022
AB  - 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<sup>−8</sup> Torr) and O<sub>2</sub> (3 × 10<sup>−8</sup> Torr). Under these conditions, we detect two transient CO species with narrow 2π<sup>*</sup> 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 2π<sup>*</sup> 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<sup>−8</sup> Torr) while maintaining the same O<sub>2</sub> pressure. At the lower CO pressure, in the CO 2π<sup>*</sup> 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. 
LB  - PUB:(DE-HGF)16
C6  - 36319417
UR  - <Go to ISI:>//WOS:000876502600007
DO  - DOI:10.1063/5.0114399
UR  - https://bib-pubdb1.desy.de/record/483446
ER  -