Franck–Condon breakdown in core-level photoelectron spectroscopy of chemisorbed CO

• Published in: Chemical physics letters Vol. 315; no. 3; pp. 194 - 200
• Main Authors: Föhlisch, A, Hasselström, J, Karis, O, Väterlein, P, Mårtensson, N, Nilsson, A, Heske, C, Stichler, M, Keller, C, Wurth, W, Menzel, D
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 24.12.1999
• Subjects: ADVANCED LIGHT SOURCE; ADVANCED LIGHT SOURCE ALS; BREAKDOWN; PARTICLE ACCELERATORS; PHOTOELECTRON SPECTROSCOPY; PHOTOIONIZATION; CHANNEL; ANGULAR-DISTRIBUTIONS; SHAPE RESONANCES; PHOTOEMISSION; SPECTRA; MOLECULAR PHOTO-IONIZATION; VIBRATIONALLY RESOLVED PHOTOELECTRON; THRESHOLD REGION; EXCITED-STATES
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(99)01194-X

The photon energy dependence of the vibrational fine structure in the C1s and O1s X-ray photoelectron main lines of chemisorbed CO on Ni(100) and Ru(0001) has been measured from 6 to 150 eV above the core-level thresholds. Significant deviations from the behavior in gas-phase CO are found. A strong dominance of the adiabatic peak towards threshold is found for the C1s, but not the O1s, lines. In the C1s lines, we observe a broad maximum of vibrational excitation 5 eV above the shape resonance. At high photon energies, Franck–Condon behavior is observed in both the C1s and O1s lines. This behavior is discussed in terms of the adsorbate electronic structure and the dynamic metallic screening upon core ionization.