Order-disorder transitions and subsurface occupation for hydrogen on Pd(111)

Felter, T. E.; Foiles, Stephen M.; Daw, Murray S.; Stulen, R. H.

doi:10.1016/0039-6028(86)90548-0

Cited by 114 publications

(41 citation statements)

References 12 publications

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“…We attempted to ''erase'' hydride features by using a variety of current and voltage pulses; however, none successfully redistributed the subsurface hydrogen. This result was expected because all theoretical studies predict subsurface sites to be substantially more stable than the bulk sites are (8,11,12,20,22,(27)(28)(29). Although the subsurface sites are the most stable sites for hydrogen, when we start the experiment, the vast majority of these sites are unoccupied.…”

Section: Resultsmentioning

confidence: 81%

“…Schematics of the corresponding potential energy diagrams (one-dimensional) for the H-Pd interaction are shown for each case. Theoretical studies have predicted a variety of shapes and energies for these curves; we have chosen the form that ref lects the consensus of the current literature describing the energy levels of the bulk, subsurface, and surface-bound hydrogen (11,12,20,22,(27)(28)(29).…”

Section: Resultsmentioning

confidence: 99%

“…The magnitude of the subsurfacesurface barrier is disputed greatly in the theoretical literature, with values ranging from 0.1 to 0.5 eV (8,11,12,20,22,(27)(28)(29). We attempted to ''erase'' hydride features by using a variety of current and voltage pulses; however, none successfully redistributed the subsurface hydrogen.…”

Section: Resultsmentioning

confidence: 99%

“…At higher coverage (Ͼ0.33 monolayer), hydrogen atoms form (͌3 ϫ ͌3)-1H, (͌3 ϫ ͌3)-2H, and 1 ϫ 1 structures on Pd{111} (8,11,12,20,22,(27)(28)(29). Salmeron and coworkers (8) demonstrated that vacancies in the 1 ϫ 1 structure also appear as protrusions.…”

Section: Resultsmentioning

confidence: 99%

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Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Sykes

Fernandez-Torres

Nanayakkara

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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We report the observation and manipulation of hydrogen atoms beneath the surface of a Pd{111} crystal by using low-temperature scanning tunneling microscopy. These subsurface hydride sites have been postulated to have critical roles in hydrogen storage, metal embrittlement, fuel cells, and catalytic reactions, but they have been neither observed directly nor selectively populated previously. We demonstrate that the subsurface region of Pd can be populated with hydrogen atoms from the bulk by applying voltage pulses from a scanning tunneling microscope tip. This phenomenon is explained with an inelastic excitation mechanism, whereby hydrogen atoms in the bulk are excited by tunneling electrons and are promoted to more stable sites in the subsurface region. We show that this selectively placed subsurface hydride affects the electronic, geometric, and chemical properties of the surface. Specifically, we observed the effects of hydride formation on surface deformation and charge and on adsorbed hydrogen on the surface. Hydrogen segregation and overlayer vacancy ordering on the Pd{111} have been characterized and explained in terms of the surface changes attributable to selective hydrogen occupation of subsurface hydride sites in Pd{111}.atomic manipulation ͉ catalysis ͉ palladium ͉ hydrogen ͉ scanning tunneling microscopy

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Section: Resultsmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Sykes

Fernandez-Torres

Nanayakkara

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…The Pd͑111͒ surface is interesting because both experimental [1][2][3][4][5][6][7] and theoretical 2,3,[8][9][10][11][12][13][14][15][16] studies show the existence of a hydrogen absorption site located between the first and second metal layer. This so-called subsurface site is energetically more favorable than the bulk site and almost as favorable as the chemisorption site on the surface.…”

Section: Introductionmentioning

confidence: 99%

Direct subsurface absorption of hydrogen on Pd(111): Quantum mechanical calculations on a new two-dimensional potential energy surface

Olsen

Philipsen

Baerends

et al. 1997

The Journal of Chemical Physics

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We have calculated a two-dimensional ͑2D͒ potential energy surface ͑PES͒ for H 2 interacting with a Pd͑111͒ surface. The geometry considered is for H 2 approaching a bridge site and dissociating into neighboring hollow sites and the subsurface sites directly below these. Density functional calculations were performed using both the local density approximation ͑LDA͒ and the generalized gradient approximation ͑GGA͒. The LDA PES gives the usual overbinding and shows no barrier ͑relative to the bottom of the H 2 potential͒ to subsurface absorption, while the GGA PES agrees with the experimental adsorption energies and has a large barrier. We have performed quantum mechanical wave packet calculations on the GGA PES to obtain the direct subsurface absorption probability. We have also calculated the barrier height's dependence on a coordinate that can be associated with a local surface vibrational mode and the results suggest that this degree of freedom should be taken into account in the dynamical calculations.

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Gas‐Surface Reactions: Molecular Dynamics Simulations of Real Systems

Brenner

Garrison

1989

Advances in Chemical Physics

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Order-disorder transitions and subsurface occupation for hydrogen on Pd(111)

Cited by 114 publications

References 12 publications

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Direct subsurface absorption of hydrogen on Pd(111): Quantum mechanical calculations on a new two-dimensional potential energy surface

Gas‐Surface Reactions: Molecular Dynamics Simulations of Real Systems

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