A direct comparison between gas-phase and solid-state Hg 5d photoionization processes

Margaritondo, G.; Rosei, R.; Weaver, J. H.; Becker, W.

doi:10.1016/0038-1098(80)90636-5

Cited by 6 publications

(1 citation statement)

References 20 publications

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“…The varying spin-orbit branching ratio results from resonances caused by spin-orbit interaction-activated interchannel coupling between final states with different j value 46 that leads to variation of the partial cross sections in the doublet. [46][47][48] According to the binding energies of the Sn 4d 5/2 components observed on the samples I-II (25.5 eV) and III (25.3 eV) we assign the oxidation state of Sn cations to 2+. 49 Note that the structure and the oxidation state of Sn-Ce mixed oxides strongly depend on the Sn concentration and the preparation conditions.…”

Section: Resultsmentioning

confidence: 95%

Hydrogen activation on Pt–Sn nanoalloys supported on mixed Sn–Ce oxide films

Neitzel

Lykhach

Škála

et al. 2014

Phys. Chem. Chem. Phys.

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We have studied the interaction of H2 with Pt-Sn nanoalloys supported on Sn-Ce mixed oxide films of different composition by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy. The model catalysts are prepared in a three step procedure that involves (i) the preparation of well-ordered CeO2(111) films on Cu(111) followed by subsequent physical vapor deposition of (ii) metallic Sn and (iii) metallic Pt. The formation of mixed Sn-Ce oxide is accompanied by partial reduction of Ce(4+) cations to Ce(3+). Pt deposition leads to the formation of Pt-Sn nanoalloys accompanied by the partial re-oxidation of Ce(3+) to Ce(4+). Subsequent annealing promotes further Pt-Sn alloy formation at expense of the Sn content in the Sn-Ce mixed oxide. Adsorption of H2 on Pt-Sn/Sn-Ce-O at 150 K followed by stepwise annealing results in reversible reduction of Ce cations caused by spillover of dissociated hydrogen between 150 and 300 K. Above 500 K, annealing of Pt-Sn/Sn-Ce-O in a hydrogen atmosphere results in irreversible reduction of Ce cations. This reduction is caused by the reaction of hydrogen with oxygen provided by the mixed oxide substrate via the reverse spillover to Pt-Sn nanoalloy. The extent of the hydrogen and oxygen spillover strongly depends on the amount of Sn in the Sn-Ce mixed-oxide. We observe an enhancement of hydrogen spillover on Pt-Sn/Sn-Ce-O at low Sn concentration as compared to Sn-free Pt/CeO2. Although the extent of hydrogen spillover on Pt-Sn/Sn-Ce-O with high Sn concentration is comparable to Pt/CeO2, the reverse oxygen spillover is substantially suppressed on these samples.

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Section: Resultsmentioning

confidence: 95%

Hydrogen activation on Pt–Sn nanoalloys supported on mixed Sn–Ce oxide films

Neitzel

Lykhach

Škála

et al. 2014

Phys. Chem. Chem. Phys.

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Delayed onset of 4d photoemission relative to the giant 4d photoabsorption of La

Aono¹,

Chiang²,

Himpsel³

et al. 1981

Solid State Communications

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The effect of crystallography on the Hg 5d branching ratios

Varma

Kime

LaGraffe

et al. 1990

The Journal of Chemical Physics

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The Hg 5d5/2 and 5d3/2 cross sections and branching ratios were measured in the photon energy range between 26 and 105 eV for Hg overlayers on Ag (100) and Cu (100). The branching ratios deviate from the nonrelativistic statistical value of 1.5, reaching values of 8.0. Data are presented that establish a direct relationship between the branching ratio and the long-range crystallographic structure of the Hg overlayers. This relationship is a consequence of the formation of a band structure from the shallow mercury 5d eigenstates.

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A direct comparison between gas-phase and solid-state Hg 5d photoionization processes

Cited by 6 publications

References 20 publications

Hydrogen activation on Pt–Sn nanoalloys supported on mixed Sn–Ce oxide films

Hydrogen activation on Pt–Sn nanoalloys supported on mixed Sn–Ce oxide films

Delayed onset of 4d photoemission relative to the giant 4d photoabsorption of La

The effect of crystallography on the Hg 5d branching ratios

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