Spin-resolved photoemission from epitaxial Au layers on Pt(111): Coverage dependence of the bandstructure and evidence of surface resonances

Vogt, B.; Schmiedeskamp, B.; Heinzmann, Ulrich

doi:10.1007/bf01323517

Cited by 14 publications

(23 citation statements)

References 21 publications

(40 reference statements)

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“…1. Peak A and peak B agree in their energetic positions and spin polarization signs with two peaks for two dimensionally grown Au/Pt(lll) [18] and a Au(lll) single-crystal [23]. For a Au(111) crystal these peaks are due to transitions from the d-derived first A a, 5 and Aa6 bands below EF into the free-electron-like final band.…”

Section: Resultssupporting

confidence: 50%

“…For a Au(111) crystal these peaks are due to transitions from the d-derived first A a, 5 and Aa6 bands below EF into the free-electron-like final band. For Au/Pt(lll) and a Au(111) single crystal only two tran-sitions are visible for our geometry at a photon energy of 15eV [18,23]. The existence of the additional structures can be understood by means of the scheme [22] in the lower part of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…For Au(111) a A34, 5 band lies 1.5 eV below the first levels corresponding to the peaks A and B. The spin polarization sign of the corresponding photoelectrons is negative [18]. This level could be involved in the silicide formation.…”

Section: Resultsmentioning

confidence: 99%

“…This indicates spin-orbit split anti-bonding levels. The energetic ordering of the spin-polarization signs i s (-, +, +, -) analogous to the ordering of the spin-polarization signs corresponding to pure Au levels [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This indicates that the Au level symmetry dominates the silicide level symmetry.…”

Section: Resultsmentioning

confidence: 99%

“…For example for Ag on Pt(111) one intensity peak consisting of emission from Ag and Pt could be separated by means of spin-resolved photoemission because of the opposite sign of the spin-polarization corresponding to the Ag peak compared with the Pt peak [17]. For emission from Au, highly spin-polarized photoelectrons have been measured [18] and for emission from Si nearly unpolarized photoelectrons [12]. A double peak (unresolved in the intensity spectrum) can be separated by means of the spin polarization because of the different signs and magnitudes• Emission from a silicide level creates no double peak and thus no pronounced structure of the polarization in the spin-resolved spectrum.…”

Section: Pacs: 7960mentioning

confidence: 99%

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Au/Si(111) and the formation of silicides at the interface examined by spin-resolved photoemission

et al. 1991

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Abstract. Au on Si(111) in the 1 x 1 structure for different coverages and in the ~/3 x ~/3R30 °, and the 5 x 1 reconstructions has been studied by means of spin-, angle-, and energy-resolved photoemission. The photoemission studies were performed at normal incidence of the circularly polarized light and normal electron emission. In addition to Au-and Si-derived peaks other highly spin-polarized peaks are observed for a coverage of 8 Au layers grown at room temperature. In keeping with previous work these peaks are interpreted as silicide peaks. The spin polarization of these peaks gives clues concerning the levels involved in the silicide formation. For a coverage of 16 Au layers on Si(111) in the 1 x 1 structure the photoemission spectra are similar to the spectra of a Au(111) crystal, but also show a contribution of the silicide peaks. For lower coverages the spectra are nearly independent of the structure (1 x 1, ]/~ x V~R30 ° or 5 x 1) and already show peaks other than the pure Au-and Si-derived peaks. The Auger signal, however, does not show contributions in addition to the pure Si signal.

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Section: Resultssupporting

confidence: 50%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Pacs: 7960mentioning

confidence: 99%

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Au/Si(111) and the formation of silicides at the interface examined by spin-resolved photoemission

et al. 1991

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Au‐Catalyzed Energy Release in a Molecular Solar Thermal (MOST) System: A Combined Liquid‐Phase and Surface Science Study

Eschenbacher,

Hemauer,

Franz

et al. 2023

ChemPhotoChem

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Molecular solar thermals (MOSTs) are molecular systems based on couples of photoisomers (photoswitches), which combine solar energy conversion, storage, and release. In this work, we address the catalytically triggered energy release in the promising MOST couple phenylethylesternorbornadiene/quadricyclane (PENBD/PEQC) on Au(111) in a combined liquid‐phase and surface science study. We investigated the system by photoelectrochemical infrared reflection absorption spectroscopy (PEC‐IRRAS) in the liquid phase, conventional IRRAS and synchrotron radiation photoelectron spectroscopy (SRPES) in ultra‐high vacuum (UHV). Au(111) is highly active towards the catalytically triggered energy release. In the liquid phase, we did not observe any decomposition of the photoswitch, no deactivation of the catalyst within 100 conversion cycles and we could tune the energy release rate of the heterogeneously catalyzed process by applying an external potential. In UHV, submonolayers of PEQC on Au(111) are back‐converted to PENBD instantaneously, even at 110 K. Multilayers of PEQC are stable up to ~220 K. Above this temperature, the intrinsic mobility of the film is high enough that PEQC molecules come into direct contact with the Au(111) surface, which catalyzes the back‐conversion. We suggest that this process occurs via a singlet‐triplet mechanism induced by electronic coupling between the PEQC molecules and the Au(111) surface.

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A new spin effect in photoemission with unpolarized light: Experimental evidence of spin polarized electrons in normal emission from Pt(111) and Au(111)

et al. 1991

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Abstract. Unpolarized light ejects spin polarized electrons from Pt(111) and Au(ll 1) even if the electron emission occurs normal to the surface. For off normal incidence of 11.8 eV, 16.9eV, and 21.2 eV radiation, and for the main peaks in the photoemission spectra, a degree of spin polarization of up to 30% or more is found for the spin polarization component Py perpendicular to the reaction plane. A crystal rotation about its surface normal does not change Py. Py is largest for transitions from bands with symmetry A~. All these experimental findings agree with a recent theoretical prediction [1] of a new spin effect by Tamura and Feder. 79.60.Cn, 71.25.Pi Spin analysis in the angle-and energy-resolved photoemission is a well established tool to gain a wealth of additional information about the electronic structure of both ferromagnetic [2] and nonmagnetic [4] crystals, surfaces and adsorbates. Most studies on nonmagnetic targets use circularly polarized radiation, since for the photoemission with unpolarized and linearly polarized radiation from non-ferromagnetic centrosymmetric [6] crystals it was for a long time generally believed (see references cited in [7,8]) that the electrons emitted normal [9] to the surface can only be unpolarized. This belief results from the description of photoemission as a "three-step process": As a consequence of the space inversion symmetry, which the infinite crystal exhibits in contrast to the semi-infinite one, no spin polarization is produced by linearly or unpolarized light in the bulk excitation step. Since transport and perpendicular surface transmission are spin independent, the photoelectrons remain unpolarized [1,10]. A theoretical treatment in the "one-step model" [7] and experiment [8] yielded, on the other hand, spin polarized electrons for the special case of normal incidence of linearly polarized radiation and three-fold surfaces. The effect shows the three-fold symmetry in the rotation diagram of the spin polarization, i.e. a sign change when the crystal is rotated about 60 degrees and it was only observed when the time reversed states with A34 and A~ symmetry are involved in the transition. The occurrence of spin polarized electrons due to this effect was, however, an exception rather than the rule; up to now the effect was only observed for transitions into the bandgap, i.e. for transitions into evanescent states [8], which emphasizes the surface sensitive nature of this effect. PACS:A spin polarization effect for far more general conditions can be expected if the radiation incidence occurs off normal. This has been predicted in recent theoretical work [1] (again in the one-step model) by Tamura and Feder. Their work deals with normal photoemi,ssion with linearly and unpolarized radiation from Pt(100) (it is in addition stated [1], that the effect should occur for practically every crystal surface): Symmetry arguments show that a spin polarization component perpendicular to the reaction plane defined by photon and photoelectron momenta is not forbidden; the ...

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Spin-resolved photoemission from epitaxial Au layers on Pt(111): Coverage dependence of the bandstructure and evidence of surface resonances

Cited by 14 publications

References 21 publications

Au/Si(111) and the formation of silicides at the interface examined by spin-resolved photoemission

Au/Si(111) and the formation of silicides at the interface examined by spin-resolved photoemission

Au‐Catalyzed Energy Release in a Molecular Solar Thermal (MOST) System: A Combined Liquid‐Phase and Surface Science Study

A new spin effect in photoemission with unpolarized light: Experimental evidence of spin polarized electrons in normal emission from Pt(111) and Au(111)

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