Shape resonance enhancement of vibrational excitations for CO chemisorbed on Ni(111) probed via inelastic electron scattering

Jeong Sook Ha, S. J. Sibener

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

This paper examines how the formation of a transient negative ion during the scattering of an electron from CO chemisorbed on Ni(111) can lead to significant enhancement in the probability for vibrationally inelastic scattering. We specifically report on the incident energy dependence for transient negative ion formation for a c(4×2) overlayer. The signature for this resonance is the energy dependence of the probability for vibrationally inelastic scattering from the CO intramolecular stretch and a CO frustrated rotation, both broadly peaking in the vicinity of 18 eV. Additional support for this scattering mechanism comes from the monotonic rise in scattering intensity for both of these vibrational modes as the final (detector) angle moves towards the surface normal under otherwise fixed kinematic conditions. We also observe the presence of weak first overtone scattering for the CO intramolecular stretch under resonant scattering conditions. All of the aforementioned observations are consistent with the formation of a Σ shape resonance which is slightly lower in energy, and has a shortened lifetime, than in the gas phase. We also report dispersion measurements along the (112) direction for the c(4×2) structure, as well as for a saturated (√7/2×√7/2) R19.1° CO/Ni(111) overlayer which give information about intermolecular couplings in these compressed structures. Discussions are presented, including wave packet arguments, which emphasize that the presence (or absence) of vibrational excitation in a given vibrational coordinate following negative ion formation can be used to infer important details about femtosecond nuclear coordinate evolution for the system in the excited state.

Original languageEnglish
Pages (from-to)10061-10069
Number of pages9
JournalThe Journal of Chemical Physics
Volume98
Issue number12
Publication statusPublished - 1993 Dec 1
Externally publishedYes

Fingerprint

Inelastic scattering
Electron scattering
Carbon Monoxide
electron scattering
inelastic scattering
Scattering
augmentation
negative ions
scattering
Negative ions
excitation
Wave packets
Excited states
wave packets
energy
vibration mode
Kinematics
kinematics
Gases
signatures

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Shape resonance enhancement of vibrational excitations for CO chemisorbed on Ni(111) probed via inelastic electron scattering. / Ha, Jeong Sook; Sibener, S. J.

In: The Journal of Chemical Physics, Vol. 98, No. 12, 01.12.1993, p. 10061-10069.

Research output: Contribution to journalArticle

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