Role of Surface States for the Epitaxial Growth on Metal Surfaces

Memmel, N.; Bertel, E.

doi:10.1103/physrevlett.75.485

Cited by 99 publications

(70 citation statements)

References 29 publications

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confidence: 51%

“…We also present full STS spectra and all features are identified by the help of the band structure. In contrast to Roos et al 16,17 the calculated band structure shows no evidence for a surface state below E F .All experiments were performed in a low-temperature ultrahigh vacuum scanning tunneling microscope ͑STM͒ system at a temperature of T = 0.3 K. 22 The single crystal Pt͑111͒ sample was prepared by repeated cycles of sputtering at room temperature ͑5-10 ML͒ with 600 eV Ar ions, flashing to 1000 K, annealing in an oxygen atmosphere of 2 ϫ 10 −6 mbar at 1000 K for half an hour and a final flash at 1200 K. This results in an Auger-clean surface ͑O and C Ͻ1% of a ML͒. STM images were recorded in the constantcurrent mode at a stabilizing current I with the bias voltage V applied to the sample.…”

contrasting

confidence: 39%

“…This bulk state is probably the one previously found by photoemission experiments. 16,17 As our calculations show, it has d yz , d zxlike symmetry. This symmetry, together with the weak dispersion, could explain the sensitivity to oxygen found in the photoemission experiments.…”

mentioning

confidence: 96%

“…This symmetry, together with the weak dispersion, could explain the sensitivity to oxygen found in the photoemission experiments. 16,17 In conclusion, we measured the dispersion of an unoccupied surface state starting at 0.3 eV above the Fermi energy. The dispersion has a strong linear contribution.…”

mentioning

confidence: 99%

“…In an early photoemission study by Roos et al, 16,17 a feature below E F was attributed to a surface state in the projected bulk band structure which was thus claimed to be occupied, but it has a surprisingly large effective mass of 1.3 m e . In contrast, inverse photoemission data show indications for an unoccupied surface state that is located approximately 0.5 eV above E F .…”

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Unoccupied surface state on Pt(111) revealed by scanning tunneling spectroscopy

et al. 2005

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We measured the dispersion of an unoccupied surface state on Pt͑111͒ by imaging scattering states at point defects and step edges using scanning tunneling spectroscopy. By comparison to first-principles electronic structure calculations the state is assigned to an sp-derived surface band at the lower edge of the projected bulk band gap. In dI / dV͑V͒ curves, the onset of the surface-state band appears as a rather broad feature. Its shape results from two spin-orbit split branches with nearly linear dispersion, one of them merging into bulk states at higher energies. DOI: 10.1103/PhysRevB.72.193406 PACS number͑s͒: 73.20.At, 72.10.Fk, 68.37.Ef, 71.15.Mb Partly occupied surface states are known to play a crucial role in chemistry, magnetism, and for the growth properties of surfaces of noble metals ͑Cu, Ag, Au͒ and late fcc transition metals ͑Ni, Pd, Pt͒. They have therefore been studied quite extensively by photoelectron spectroscopy. 1 As was shown more than ten years ago, surface states and their interaction with defects can be studied on a local scale by scanning tunneling spectroscopy ͑STS͒. 2,3 Recent publications in this field deal with the interaction of surface states with atomic adsorbates 4,5 or of the interaction of adsorbates mediated by surface states, 6 with lifetime effects, 7 the Stark effect, 8 or even spin-orbit-induced spin splitting similar to the Rashba effect in two-dimensional electron systems of semiconductor heterostructures. 9-11 For noble-metal ͑111͒ surfaces, it is well known that a partly occupied crystalinduced surface state resides far inside the projected bulk sp-band gap at the center of the Brillouin zone. This sp-like surface state is usually referred to as the Shockley surface state. 12 The situation is more complex for the late fcc transition metals. Ni͑111͒ has a spin-split surface state just at the bottom of the band gap. Its minority spin state is unoccupied, whereas the majority spin state is partly occupied. 13,14 In contrast, the corresponding surface state on Pd͑111͒ is unoccupied and far above the Fermi energy E F . 15 The effective mass in both cases is comparable to the noble-metal case.For Pt͑111͒ the situation is controversial. In an early photoemission study by Roos et al.,16,17 a feature below E F was attributed to a surface state in the projected bulk band structure which was thus claimed to be occupied, but it has a surprisingly large effective mass of 1.3 m e . In contrast, inverse photoemission data show indications for an unoccupied surface state that is located approximately 0.5 eV above E F . 18 Later, this was confirmed theoretically and substantiated by comparison to lifetime measurements of image potential states. 19,20 Up to now there is no direct photoemission measurement of the dispersion of an unoccupied surface state, nor it is visible in previous STS studies. 21 This means that there are no experimental data so far to clarify the situation.Here we show that an unoccupied surface state on Pt͑111͒ can be directly imaged by STS in the form of scat...

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confidence: 51%

contrasting

confidence: 39%

mentioning

confidence: 96%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Unoccupied surface state on Pt(111) revealed by scanning tunneling spectroscopy

et al. 2005

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Electronic Surface States and the Hydrogen Dissociation Barrier

Bertel

1997

phys. stat. sol. (a)

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Surface states contribute significantly to the charge density in front of metal surfaces. Owing to the Pauli principle, this yields a repulsive contribution in the physisorption potential for closed‐shell adsorbate particles, such as rare‐gases or H2. In the case of rare‐gas adsorption the surface state induced repulsion can be directly measured by means of high‐resolution photoemission. The additional repulsive contribution influences also the barrier height in dissociative adsorption. This is demonstrated for f.c.c. (111) and f.c.c. (110) surfaces by adjusting the surface state occupancy with a variety of suitable adsorbates and monitoring the associated changes in the dissociation probability of H2.

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