Electron Spectroscopy Using Metastable Atoms as Probes for Solid Surfaces

Harada, Yoshiya; Masuda, S.; Ozaki, Hiroyuki

doi:10.1021/cr940315v

Cited by 365 publications

(350 citation statements)

References 319 publications

(1,025 reference statements)

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“…Governed by the overlap between projectile and target orbitals, the probability of this process is proportional to the density of occupied states on the outermost substrate surface. 29 On the other hand, since the emitted electron originates from the helium atom, the density of empty states in the conduction band need not be taken into consideration for the interpretation of the MIES data. 21 Starting from the bottom spectrum of the clean MgO surface in Figure 1a, there is a continuous build up of the water-induced features 1b 1 , 3a 1 , and 1b 2 and an attenuation of the substrate intensity visible.…”

Section: Resultsmentioning

confidence: 99%

Dissociation of Water at the MgO(100)−Water Interface: Comparison of Theory with Experiment

Johnson¹,

Stefanovich²,

Truong³

et al. 1999

J. Phys. Chem. B

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Dissociative chemisorption of H 2 O at the MgO(100)-water interface has been investigated both experimentally and theoretically. In particular, metastable impact electron spectroscopy (MIES) was used to image the density of occupied states on the MgO(100)/Mo(100) surface for various degrees of water exposure. After multilayer water desorption, spectral features typical of surface hydroxyls are present. To further study the possibility of dissociative chemisorption of water, a theoretical and computational method called CECILIA (combined embedded cluster at the interface with liquid approach) was used to calculate the geometry, energetics, and electronic density of states (DOS) for interfacial species. Consistent with experiment, our theoretical results predict that dissociative adsorption of H 2 O at the MgO(100)-water interface is energetically more favorable than molecular adsorption. The stabilization of charged OH -and H + interface adsorbates is due to polarization of the surrounding solvent.

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Section: Resultsmentioning

confidence: 99%

Dissociation of Water at the MgO(100)−Water Interface: Comparison of Theory with Experiment

Johnson¹,

Stefanovich²,

Truong³

et al. 1999

J. Phys. Chem. B

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“…This approach has been used, beginning with Hans Siegbahn and coworkers early designs in the 1970's 10,11,12 , in all ambient pressure XPS instruments that have been designed to date. 13,14,15,16,17,18,19,20,21 A similar approach has been taken in the application of meta-stable impact electron spectroscopy (MIES) 22,23 for the study of surfaces, including liquids, at elevated pressures. 24 In addition to the scattering of electrons by gas molecules, there are other obstacles to overcome in ambient pressure XPS instruments, namely that the X-ray source (synchrotron or anode) and the electron analyzer have to be kept under UHV.…”

Section: Introductionmentioning

confidence: 99%

A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces

Starr

Wong

Worsnop

et al. 2008

Phys. Chem. Chem. Phys.

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We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50…150 µm is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100…1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer.The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic

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“…The PI process also takes place in the BCP-K system, reflecting the low work function of the K layers. 12 It turns out from Figs. 2͑a͒ and 2͑b͒ that the BCPderived bands are clearly observed even in the submonolayer region, since the PI process takes place selectively at the topmost layer.…”

Section: Resultsmentioning

confidence: 93%

“…12,13 On an insulating organic film, the metastable atoms decay via Penning ionization, where a valence electron of the film fills the He ‫ء‬ 1s hole and the 2s electron is emitted simultaneously. This process yields a single-hole spectrum as in the case of ultraviolet photoemission spectroscopy ͑UPS͒.…”

Section: Introductionmentioning

confidence: 99%

Level alignment of gap state at organic-metal interface

Aoki

Toyoshima

Kamada

et al. 2009

Journal of Applied Physics

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Electron emission spectra resulting from thermal collision of He ‫ء‬ ͑2 3 S͒ atoms with 2,9-demethyl-4,7-diphenyl-1,10-phenanthroline ͑BCP͒ films deposited on metal substrates were measured to characterize gap states emerged at the organic-metal interface. For BCP on Au, the gap state is originated from weak chemisorption and serves as a mediator of metal wave functions to the first layer. For BCP on K, organic-metal complex is formed by spontaneous diffusion, yielding the gap states delocalized over the film. In the interfacial region, all the gap state reveals an incommensurate shift with the valence band top of the film, indicating the breakdown of the Schottky-Mott model as evaluating the transport characteristics in organic-metal system.

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Electron Spectroscopy Using Metastable Atoms as Probes for Solid Surfaces

Cited by 365 publications

References 319 publications

Dissociation of Water at the MgO(100)−Water Interface: Comparison of Theory with Experiment

Dissociation of Water at the MgO(100)−Water Interface: Comparison of Theory with Experiment

A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces

Level alignment of gap state at organic-metal interface

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