Low-energy electron microscopy of CO/Pt(111) surface diffusion by nonequilibrium coverage profile evolution

Yim, Chi Ming; Man, Ka Lun; Xiao, Xudong; Altman, Michael S.

doi:10.1103/physrevb.78.155439

Cited by 28 publications

(23 citation statements)

References 36 publications

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“…zero net field occurs in the space between them, as discussed by previous authors. 29 Thus, the onset energy provides a measure of the vacuum level position for each particular spectrum. The sample work function is typically higher than that of the LaB 6 thermionic electron emitter in the LEEM, so that the LEER spectra generally have an onset that occurs at positive energy.…”

Section: A Cu(001)mentioning

confidence: 99%

Low-energy electron reflectivity of graphene on copper and other substrates

Srivastava¹,

Gao²,

Widom³

et al. 2013

Phys. Rev. B

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The reflectivity of low energy electrons from graphene on copper substrates is studied both experimentally and theoretically. Well-known oscillations in the reflectivity of electrons with energies 0 -8 eV above the vacuum level are observed in the experiment. These oscillations are reproduced in theory, based on a first-principles density functional description of interlayer states forming for various thicknesses of multilayer graphene. It is demonstrated that n layers of graphene produce a regular series of 1  n minima in the reflectance spectra, together with a possible additional minimum associated with an interlayer state forming between the graphene and the substrate. Both (111) and (001) orientations of the copper substrates are studied. Similarities in their reflectivity spectra arise from the interlayer states, whereas differences are found because of the different Cu band structures along those orientations. Results for graphene on other substrates, including Pt(111) and Ir(111), are also discussed.

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Section: A Cu(001)mentioning

confidence: 99%

Low-energy electron reflectivity of graphene on copper and other substrates

Srivastava¹,

Gao²,

Widom³

et al. 2013

Phys. Rev. B

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“…Information on mass transport is obtained here from observations of the temporal evolution of nonequilibrium coverage profiles that are prepared by laser induced thermal desorption (LITD). Diffusion experiments are often carried out by monitoring the relaxation of spatial coverage gradients [18][19][20], generated either by equilibrium fluctuations or imposed externally. Since the diffusion equation is a differential equation of second order in the space variable, r, and first order in the time variable, t, it predicts that an evolving coverage profile, ðr; tÞ, is only a function of the scaled variable ¼ r 2 =t.…”

mentioning

confidence: 99%

Anomalous Mass Transport in the Pb Wetting Layer on the Si(111) Surface

2008

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The temporal evolution of nonequilibrium coverage profiles in the Pb wetting layer on the Si(111) surface is studied using low energy electron microscopy. The initial coverage step profile propagates rapidly at a constant velocity with an unperturbed shape. A model is proposed that attributes this nonclassical equilibration behavior to the diffusion of thermally generated adatoms on top of the wetting layer. This model can account for the observed convectionlike mass transport, as well as its dramatic dependence on Pb coverage. Such anomalous mass transport is believed to facilitate the remarkably efficient self-organization of uniform Pb quantum island height on the Si(111) surface that was observed previously.

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“…30,31 The transition from LEEM to MEM is identifiable by a sharp rise of image intensity as the incident electron energy is reduced. Two measurement modes were used to determine work function changes: (i) repeatedly recording the MEM to LEEM transition intensity curves during Fe deposition and plotting the shifting voltage at a fixed fraction (50%) of the saturation MEM intensity, and (ii) continuously recording the image intensity at fixed energy in the MEM to LEEM transition region during deposition.…”

Section: Methodsmentioning

confidence: 99%

Growth, magnetism and ferromagnetic thickness gap in Fe films on the W(111) surface

Zdyb

Bauer

et al. 2013

Phys. Rev. B

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The growth, structure, and magnetism of Fe films on the W(111) surface were investigated using low energy electron microscopy (LEEM) and diffraction (LEED), spin polarized LEEM (SPLEEM), and work function measurements. In contrast to an earlier report that Fe grows with fcc structure following initial pseudomorpic layer growth, we observe no evidence of the formation of fcc Fe over the entire thickness range studied, up to 18 monolayers (ML). Observations are instead consistent with the formation of a well-ordered, laterally (tensile) strained bcc Fe layer that gradually relaxes vertically and develops increasing disorder with increasing thickness. Ferromagnetic order appears at 6 ML, but surprisingly vanishes at 8 ML, and reappears just as suddenly at 9 ML during Fe deposition at room temperature. Ferromagnetism between 6 and 8 ML also vanishes at only 5 deg above room temperature. The magnetization direction of a monodomain structure remains constant before and after the ferromagnetic thickness gap at 8-9 ML until the formation of a multidomain structure at about 12 ML. Variations of exchange asymmetry in spin-polarized elastic electron scattering are also observed with increasing film thickness, particularly above 12 ML, that indicate changes in the spin-polarized electron band structure above the vacuum level. The evolution of magnetism and exchange asymmetry with increasing thickness and the appearance of the ferromagnetic gap are attributed to structural and morphological changes in the strained Fe layer, which eventually lead to a relaxed although highly disordered bcc Fe layer.

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Low-energy electron microscopy of CO/Pt(111) surface diffusion by nonequilibrium coverage profile evolution

Cited by 28 publications

References 36 publications

Low-energy electron reflectivity of graphene on copper and other substrates

Low-energy electron reflectivity of graphene on copper and other substrates

Anomalous Mass Transport in the Pb Wetting Layer on the Si(111) Surface

Growth, magnetism and ferromagnetic thickness gap in Fe films on the W(111) surface

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