Introduction
Research in this laboratory uses a high-resolution electron-energy-loss
spectrometer in conjunction with dosing from a high-intensity and variable
kinetic energy supersonic beam. Activities include: mapping out the
surface phonon dispersion curves of clean and adsorbate covered surfaces
in
order to ascertain how metallic bonding differs at the interface of a
material as compared to its bulk behavior; synergistic effects during
metallic oxidation involving electrons and, shortly, UV illumination;
electron shape resonances which shed light on the femtosecond evolution of
electron-adsorbate dynamics; and, most recently,
metallic oxidation involving energetic reagents such as
accelerated molecular oxygen and supersonic beams of atomic oxygen
including some electronic state preparation.
The Machine
The apparatus consists of two main parts, the UHV chamber and the beamline.
The UHV system has an upper and a lower level. The upper level is equipped with an ion gun, Auger and LEED for sample preparation and characterization. The lower level is in plane with the beam line and contains the RGA and HREELS. The RGA is used for both the analysis of background gas and characterization of the molecular beam through time-of-flight analysis.
The beamline has three differentially pumped regions operating at
progressively lower pressures.
The beam is incident on the sample at an angle of 15º with respect to
surface normal. The
beam spot is coincident with the electron beam of the HREEL spectrometer.
Shown above is a schematic of
the reactive beam scattering machine; for a mildly incomprehensible
picture click
here.
Recent Results
For a short description of
our experiments on kinetic energy effects on the oxidation of
Ni(111) using molecular oxygen beams, click here. For a short description of
our experiments on the effects on oxidation of Ni(111) under
electron irradiation, click here.References
34. "Surface phonon spectroscopy of nickel (111) studied by inelastic electron scattering"
37. "Inelastic electron scattering study of nickel(111) surface phonons"
40. "Measurement of low energy frustrated vibrational modes of carbon
monoxide on nickel (111)
50. "Shape resonance enhancement of vibrational excitations for carbon
monoxide chemisorbed
53. "Surface phonon dispersion of p(2x2)O/Ni(111)"
57. "Interadsorbate interactions in the c(4x2) NO/Ni(111) system"
58. "Electron-stimulated oxidation of Ni(111) at low temperature"
61. "Inelastic electron scattering study of metallic oxidation:
Synergistic effects
73. "Kinetic energy effects on the oxidation of Ni(111) using O2 molecular beams"
75. "Enhanced oxidation rate of Ni(111) by atomic oxygen"
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