Forward focusing of Auger and Kikuchi electrons for surface structure determination: Ni(100) and oxidized Mg(0001)

Cronacher, H.; Heinz, K.; Müller, K.; Xu, Muliang; Hove, M. A. Van

doi:10.1016/0039-6028(89)90083-6

Cited by 24 publications

(8 citation statements)

References 20 publications

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“…As the energy is increased, the intensities of these beams first pass a succession of maxima and minima and then gradually fade away. When the diffracted beams disappear, several experiments have shown that the electrons are reflected in all directions with broad intensity maxima at directions that can be associated with crystal chains of atoms [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] . Because of this drastic change in the angular pattern, a LEED experiment extended into this energy region is often referred to as medium-energy electron diffraction ͑MEED͒.…”

Section: Introductionmentioning

confidence: 99%

Diffraction effects in the incident and exit paths of electrons backscattered from Cu(001) at medium energies

et al. 1999

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We analyze experimentally and theoretically the angular distribution of electrons backscattered from Cu͑001͒ at medium energies. We present polar intensity plots ͑PIP's͒ of backscattered electrons with important qualitative differences with PIP's of x-ray photoemitted electrons acquired in similar conditions. In particular, our PIP's of backscattered electrons present peaks, ascribed to diffraction effects in the incident part of the electron trajectory, and a symmetry that are not observed in the PIP's of photoelectrons. The theoretical analysis has been made using a model presented recently to explain the change of the angular pattern in passing from low to medium energies. We present calculations performed including curved-wave-front and multiplescattering effects that are in very good agreement with the experiments. The results show that the main structures in the PIP's are produced by forward-focusing interferences ͑similar to those of photoelectron diffraction͒ in either the incoming or the outgoing parts of the electron trajectory, and by interferences between waves with important forward scattering in both the incoming and outgoing parts of the electron trajectory.

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Section: Introductionmentioning

confidence: 99%

Diffraction effects in the incident and exit paths of electrons backscattered from Cu(001) at medium energies

et al. 1999

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“…Very surprisingly, when the diffracted beams disappear the angular pattern becomes similar to those measured in XPD and AED experiments. [5][6][7][8][9][10][11][12][13][14][15][16] Because of this new characteristic, a LEED experiment extended into this energy region is often referred to as medium-energy electron diffraction ͑MEED͒. The high counting rates in MEED and the direct relation of the structures in the angular pattern with the real lattice have been exploited in different crystallographic studies.…”

Section: Introductionmentioning

confidence: 99%

“…The high counting rates in MEED and the direct relation of the structures in the angular pattern with the real lattice have been exploited in different crystallographic studies. 9,11,12,15 However, in spite of some successful applications, the poor understanding of the origin of the XPD/AED-like structures has hindered the use of MEED as a crystallographic tool beyond a qualitative level. It is generally assumed that the electron undergoes an inelastic collision at an atomic site and that thereafter it evolves as having been emitted from that site.…”

Section: Introductionmentioning

confidence: 99%

“…It is generally assumed that the electron undergoes an inelastic collision at an atomic site and that thereafter it evolves as having been emitted from that site. 9,11,16 This artificial break of the electron trajectory into an incident and an exit path renders the problem tractable with the XPD/AED models, but eludes the central question of explaining why the angular pattern changes between the LEED and the MEED regimes.…”

Section: Introductionmentioning

confidence: 99%

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Angular distribution of backscattered electrons with excitation of phonons and plasmons

Alvarez

Zampieri

1998

Phys. Rev. B

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The ''elastic'' backscattering of electrons from crystalline surfaces has two regimes: at low energies the angular distribution has the narrow peaks characteristic of the Bragg diffraction, but at medium energies the angular distribution changes and becomes similar to that observed in Auger and x-ray photoelectron diffraction. We have presented recently a model that explains this change of the angular distribution in terms of the excitation/absorption of phonons during the scattering. In this paper we apply the model to the case of the electron backscattering from Al͑111͒, finding good agreement between calculated and measured angular distributions. In addition to this, we present a decomposition of the calculated intensity into the contributions of the scattering events with excitation and/or absorption of n phonons (0рnр8), and we compare these contributions with the angular distributions of electrons reflected having excited n plasmons (0рnр8). All these results are used to elucidate the nature of the change of the angular pattern in passing from low to medium energies.

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“…In our survey, we included the adsorption sites suggested by earlier studies 6,11,12 along with a number of other positions above and below the surface. 18 Of these, the stable sites are sketched in Fig.…”

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confidence: 99%

Mg(0001) surface oxidation: A two-dimensional oxide phase

2004

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First-principles electronic structure calculations and angle-scanned x-ray photoelectron diffraction experiments reveal the geometrical structure of the Mg͑0001͒ surface upon oxidation. In contrast to previous studies of Mg͑0001͒ oxidation and unlike the case of aluminum oxidation we determine a surface oxide structure, consisting of mixed oxygen-magnesium layers on top of an almost unchanged Mg͑0001͒ surface. This unusual, directionally bound, surface oxide is locally formed already at very low dosing, corresponding to total coverages of 0.1 monolayer ͑ML͒, and grows laterally with increasing oxygen coverage up to at least 3 ML total coverage.

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Forward focusing of Auger and Kikuchi electrons for surface structure determination: Ni(100) and oxidized Mg(0001)

Cited by 24 publications

References 20 publications

Diffraction effects in the incident and exit paths of electrons backscattered from Cu(001) at medium energies

Diffraction effects in the incident and exit paths of electrons backscattered from Cu(001) at medium energies

Angular distribution of backscattered electrons with excitation of phonons and plasmons

Mg(0001) surface oxidation: A two-dimensional oxide phase

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