Effects of coadsorbed atomic oxygen on the electron-stimulated desorption of neutral NO from Pt(111)

Journal Article · Wed Jan 15 00:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.1373· OSTI ID:5132956

Burns, A R; Stechel, E B; Jennison, D R; Orlando, T M ^[1]

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1. Sandia National Laboratories, Division 1151, Albuquerque, New Mexico 87185 (United States)

We examine the effects of an electronegative coadsorbate on the electron-stimulated-desorption (ESD) yield and desorbate energies (translational and internal) of a chemisorbed molecule. Specifically, we use laser resonance-ionization spectroscopy to characterize the ESD of neutral NO from a Pt(111) surface precovered with atomic oxygen. With increasing oxygen coverage (up to 0.75 monolayer), we observe the following for the NO desorbate: (1) an exponential increase in specific yield, (2) increased translational energy, (3) decreased vibrational energy, (4) decreased rotational energy, and (5) a growing propensity to produce the upper spin-orbit level of the spin-orbit-split electronic ground state. The first three observations are understood in terms of an O-induced reduction in charge transfer from the substrate into the adsorbate 2{pi} molecular level to screen the electronic excitation (5{sigma}{sup {minus}1}). This has the dual effect of reducing the Auger decay rate 5{sigma}{sup 1}2{pi}{sup 2}(NO){r arrow}5{sigma}{sup 2}2{pi}{sup 0}(NO{sup +}), and of lowering the NO vibrational excitation. The consequences of a reduced Auger decay rate are a larger ESD yield and more desorbate translational energy. We argue that the spin-orbit propensity arises from an O-induced rotational hindering of the NO excited state. A hindered NO{sup +} rotor, ionized after Auger decay, is reneutralized by a strongly spin-orbit-split Pt(111) substrate at a greater rate into the upper level than into the lower level.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5132956
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 45:3; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
36 MATERIALS SCIENCE
NITROGEN OXIDES
DESORPTION
PLATINUM
SORPTIVE PROPERTIES
AUGER EFFECT
GROUND STATES
OXYGEN
ROTATIONAL STATES
VIBRATIONAL STATES
CHALCOGENIDES
ELEMENTS
ENERGY LEVELS
EXCITED STATES
METALS
NITROGEN COMPOUNDS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENTS
664400* - Experimentally Derived Information on Atomic & Molecular Properties- (1992-)
360204 - Ceramics
Cermets
& Refractories- Physical Properties