Adsorbed states of H on Ni(111) at 100 K: A vibrational study

Yanagita, Hiroshi; Sakai, Jiro; Aruga, Tetsuya; Takagi, Noriaki; Nishijima, Michiharu

doi:10.1103/physrevb.56.14952

Cited by 20 publications

(16 citation statements)

References 28 publications

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“…The asymmetric and symmetric modes are shifted in energy and appear at 954 ͑706͒ and 1170 (834) cm Ϫ1 , respectively. 8,10 In addition to these dominant losses, we observe a smaller peak at 1744 (1310) cm Ϫ1 , which is readily identified as v as (2) . This is in contrast to the case of the (2ϫ2)-2H phase, where complex features are found.…”

Section: Figure 1͑a͒mentioning

confidence: 76%

“…A Ni͑111͒ sample was cleaned in the manner described elsewhere. 8 For a clean surface, a sharp 1ϫ1 LEED pattern was obtained, and the EELS showed no trace of impurity on the surface. The measurements were conducted at 90 K for the (2ϫ2)-2H and (1ϫ1)-H phases, with coverages of 0.5 and 1.0 ML, respectively.…”

Section: Methodsmentioning

confidence: 98%

“…͑800͒ cm Ϫ1 were previously observed, and assigned to the asymmetric (v as ) and symmetric (v s ) stretching vibrational modes of H ͑D͒ adsorbed in the three fold hollow sites, respectively. [8][9][10][11] Due to the advanced sensitivity of the EELS spectrometer, 12 we can resolve the fundamental mode further. Peaks appear for H species at 774 and 1054 cm Ϫ1 in the higher-and lower-energy sides of the dominant losses ͑732 and 1094 cm Ϫ1 ), respectively.…”

Section: Methodsmentioning

confidence: 99%

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Overtones of H vibrations at Ni(111): Formation of delocalized states

et al. 2001

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Section: Figure 1͑a͒mentioning

confidence: 76%

Section: Methodsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

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Overtones of H vibrations at Ni(111): Formation of delocalized states

et al. 2001

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“…11 The shoulder observed at the lower-energy side of the 1170-cm Ϫ1 loss is due to the residue of the (2ϫ2)-2H phase on the surface. 10 The peaks below 300 cm Ϫ1 are attributed to the Ni phonons.…”

Section: Methodsmentioning

confidence: 99%

Direct evidence for the two-phonon bound states on the H/Ni(111) surface

et al. 2001

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We have investigated multiple losses and overtones of H vibrations at Ni͑111͒ by using electron-energy-loss spectroscopy. We mapped the energies along the ⌫ M direction of the surface Brillouin zone, and found two branches outside the two-phonon continua. This gives direct evidence of the existence of two-phonon bound states. Applying a one-dimensional model of coupled anharmonic oscillators, we derive the anharmonicity and discuss the localized property of the bound states.

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“…Christmann's low energy electron diffraction (LEED) studies of hydrogen on Ni(111) revealed the formation of an ordered (2x2)-2H hexagonal structure with equal occupation of the hexagonal close packed (hcp) and face centered cubic (fcc) three-fold hollow sites 2 . The vibrational study by Yanagita et al 15 shows that hydrogen forms (2x2)-2H island structures on the Ni(111) surface, with no evidence of quantum tunneling effects and vibrational modes at 2.2 THz and 3.1 THz, shifting to 2.8…”

Section: Introductionmentioning

confidence: 99%

First Principles Calculations of Electrochemically Controlled Hydrogen Mobility and Uptake at the Ni(111)H2O Interface

Taylor¹,

Kelly²,

Neurock³

2005

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The binding of hydrogen on Ni(111) in the presence of an water is considered using both a bilayer and a saturated model of the solvent environment. The presence of a water bilayer did not change the binding energies or geometry of hydrogen on the Ni (111) compared to adsorption in ultra-high vacuum. Using the saturated model (four bilayers over the surface) we also monitored the change in hydrogen binding as a function of electrochemical potential. Binding energies for hydrogen at the hcp and octahedral sites shifted endothermically as the potential was made more anodic, indicating that reductive partial charge transfer occurs. Binding at the tetrahedral site was found to be partially oxidizing. Calculation of vibrational modes allowed the extrapolation of ab initio results to ambient and elevated temperatures. Surface Pourbaix diagrams were constructed illustrating the stability of various phases on the Ni(111) surface as a function of pH and potential.3

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Adsorbed states of H on Ni(111) at 100 K: A vibrational study

Cited by 20 publications

References 28 publications

Overtones of H vibrations at Ni(111): Formation of delocalized states

Overtones of H vibrations at Ni(111): Formation of delocalized states

Direct evidence for the two-phonon bound states on the H/Ni(111) surface

First Principles Calculations of Electrochemically Controlled Hydrogen Mobility and Uptake at the Ni(111)H2O Interface

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