Water adsorption on bromine-covered copper single crystal surfaces

Bange, K.; Döhl, R.; Grider, D.E.; Sass, J.K.

doi:10.1016/0042-207x(83)90604-8

Cited by 47 publications

(17 citation statements)

References 14 publications

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“…The more ionic character of the bond is consistent, for example, with the greatly enhanced affinity of water for halogenated Cu and Ag surfaces [170][171][172]. After higher temperature exposures of chlorine on these metals, formation of surface and subsurface chlorides is observed [173][174][175].…”

Section: Halidessupporting

confidence: 54%

Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Marshall

Medlin

2011

Surface Science Reports

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Section: Halidessupporting

confidence: 54%

Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Marshall

Medlin

2011

Surface Science Reports

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“…(ii) Br (as an acceptor) and CH 3 Br (as a donor) have opposite dipoles on the surface. 18,19,24 The consistent shift to higher temperatures of the CH 3 Br ∆p-TPD ( Figure 1) and ∆ -TPD (see discussion below) as exposure to UV light increases suggests that attractive interactions between the coadsorbates (Br atoms and CH 3 Br molecules) dominate. Consequently, stabilization of the ground electronic state may lead to more efficient quenching of the exited state and therefore the dissociation cross-section should further decrease.…”

Section: Resultsmentioning

confidence: 99%

“…It is evident that, as bromine atoms accumulate on the surface, a shift to higher temperatures is observed in the derivative spectra. This reflects the stabilization of the methyl bromide molecules due to the presence of the bromine atoms, as a result of attraction between opposite dipoles (bromine) +0.8 eV/0.33 ML 24 and CH 3 Br ) -1.4 eV/0.22 ML 18 ). A comparison of the ∆p-TPD and the d(∆ )/dT spectra around 450 K is shown in the inset of Figure 3a, indicating a very good overlap between the two.…”

Section: ∆ -Tpdmentioning

confidence: 99%

Photoinduced Fragmentation of Multilayer CH₃Br on Cu/Ru(001)

Livneh¹,

Asscher²

2003

J. Phys. Chem. B

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The broadband UV (230-420 nm) photoinduced chemistry of CH 3 Br adsorbed on Cu(2ML)/Ru(001) in the coverage range of 1-50 ML was studied by monitoring the desorption products (∆p-TPD mode) in combination with post irradiation work function change measurements before and during surface heating (∆ -ΤPD mode). ∆ measurements enabled us to follow multilayer restructure and desorption of parent molecules and photochemical reaction products in the temperature range of 80-700 K. Methyl radicals accumulated on the surface are the precursor for the thermal formation of methane and ethylene at 450 K. Dehydrogenation of the methyl group is the rate-limiting step of the surface reaction resulting in the formation of these molecules. Based on work function change measurements, an estimate of the adsorbed methyl dipole moment is µ 0 ) 0.48 D. Dissociative electron attachment (DEA) driven CH 3 Br dissociation produced CH 3 and CH 2 fragments within the parent molecules multilayer matrix. At the multilayer coverage range, ∆ increases by up to 1.1 eV after 10 min UV irradiation. Model calculations qualitatively describe the post irradiation work function changes induced by the embedded photofragments (mostly Br -ions) inside the CH 3 Br dielectric film.Comparison of the ∆ -TPD spectra on Cu(2ML)/Ru(001) to those on clean Ru(001) indicates that the nature of the molecule-surface interaction and the structure of the first few layers strongly influence the resulting photochemistry at layer thickness up to at least 20 ML.

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“…This assumption is based on the expected similarity with the identical ordered structure formed by chlorine on Cu(111) 42 and on Ru(001). 43 At 1 ML of coverage the work function change induced by bromine atoms is +0.8 and -0.32 V on Cu(111) 41 and Ru(001), 29 respectively.…”

Section: Ch 3 Br On Cu(2 Ml)/ru(001)mentioning

confidence: 99%

“…This is measured by subtracting the initial reading at 82 K, prior to the adsorption of 6 L of CH 3 Br on the Cu/Ru(001) surface, from the ∆ value detected after sample heating to 550 K. Bromine forms a ( 3 × 3)R30°structure on Cu(111). 41 We assume that a similar structure is formed on both Ru(001) and Cu(2 ML)/Ru(001), defining this as 1 ML of bromine coverage (namely, 1 ML ) Br/Ru ) 0.33). This assumption is based on the expected similarity with the identical ordered structure formed by chlorine on Cu(111) 42 and on Ru(001).…”

Section: Ch 3 Br On Cu(2 Ml)/ru(001)mentioning

confidence: 99%

Surface Chemistry of CH₃Br and Methyl Modified by Copper Deposition on Ru(001)

Livneh

Asscher

1999

J. Phys. Chem. B

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The chemistry of methyl bromide on Cu/Ru(001) has been studied utilizing work function change (∆ ) and temperature-programmed desorption (TPD) measurements. The remarkable modification in the methyl fragments dehydrogenation at the completion of a single copper layer and the significant difference in reactivity of the Cu(2 ML)/Ru(001) or Cu(111) surfaces are the focus of this study. A decrease in work function at the completion of 1 ML CH 3 Br of 2.15 ( 0.02 eV and 1.33 ( 0.05 eV was measured, respectively, for Ru (001) and Cu(2 ML)/Ru(001) held at 82 K. Methyl bromide does not dissociate upon adsorption on clean or the copper-covered surfaces, and it is bound with the bromine down. Copper modifies the reactivity of the Ru substrate, gradually decreasing the dissociated fraction of CH 3 Br from 0.55 of the initial one monolayer on clean Ru(001) to 0.06 on Cu(2 ML)/Ru(001), probably because of defects in the copper layer. The methyl fragment dehydrogenation rate slows as the copper coverage increases. At a narrow copper coverage range between 0.8 and 0.95 ML, adsorbed hydrogen and methyl fragments coexist on the surface in the temperature range 230-280 K. Sequential decomposition channels of the parent molecules and the methyl fragment lead to a unique enhancement of methane production rate, this on the account of further hydrocarbon dehydrogenation, as reflected in both ∆p and ∆ TPD measurements. Methane is formed on top of copper terraces as a result of "spill-over" of both methyl and hydrogen atoms, similar to the chemistry over Cu(111) and Cu(110) single-crystal surfaces. The dipole moment of adsorbed methyl is reported here for the first time on metal surfaces, being 0.48 D on top of Cu(2 ML)/Ru(001).

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Water adsorption on bromine-covered copper single crystal surfaces

Cited by 47 publications

References 14 publications

Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Photoinduced Fragmentation of Multilayer CH₃Br on Cu/Ru(001)

Surface Chemistry of CH₃Br and Methyl Modified by Copper Deposition on Ru(001)

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Water adsorption on bromine-covered copper single crystal surfaces

Cited by 47 publications

References 14 publications

Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Surface-level mechanistic studies of adsorbate–adsorbate interactions in heterogeneous catalysis by metals

Photoinduced Fragmentation of Multilayer CH3Br on Cu/Ru(001)

Surface Chemistry of CH3Br and Methyl Modified by Copper Deposition on Ru(001)

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Photoinduced Fragmentation of Multilayer CH₃Br on Cu/Ru(001)

Surface Chemistry of CH₃Br and Methyl Modified by Copper Deposition on Ru(001)