Vibrational frequencies of halogens adsorbed on Ag (100) based on ab initio cluster model calculations

Illas, Francesc; Rubió, J.; Ricart, Josep M.; Garrido, José Antonio

doi:10.1016/0022-0728(86)90044-6

Cited by 20 publications

(5 citation statements)

References 15 publications

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“…For F, the frequencies lie in the sequence Rh, Pd (∼210 cm -1 ) > Cu, Ag, Au (∼200 cm -1 ) > Pt (190 cm -1 ). The trends for the (100) surfaces are also similar to those discussed above, and perhaps it is worth commenting that the present calculated values are slightly larger than those previously reported for halogens on Ag(100) using a Hartree−Fock cluster model approach, although the difference can be entirely ascribed to coverage effects …”

Section: General Trends In the Adsorption Of Halogens On Cu Rh Pd Ag ...supporting

confidence: 88%

“…Halogens on metals have also been a trial field for many theoretical techniques, which go from simple empirical quantum chemical models to ab initio cluster model studies based either on Hartree−Fock − (HF) or various implementations of DFT. , Pacchioni et al used methods of analysis of the chemisorption bond of halogens on rather small cluster model representations of Ag(111) . These techniques included the constrained-space orbital variation method − and the analysis of dipole moment curves .…”

Section: Introductionmentioning

confidence: 99%

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A Systematic Study of the Structure and Bonding of Halogens on Low-Index Transition Metal Surfaces

2006

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The structure and bonding of halogens on various transition metal low-index surfaces has been studied by means of density functional theory (DFT) calculations using periodic slabs to model the surface. This approach is shown to be capable of reproducing available experimental data of naked and halogen-covered surfaces. Periodic trends are discerned and discussed for several properties, including metal-halogen bond distances and vibrational frequencies, adsorption energies, and bond ionicities, which have been evaluated by a Bader population analysis of the corresponding density. A simple correlation is discerned, relating the bond ionicity to the metal work function, so that higher work function surfaces are associated with more covalent bonding. Periodic trends in bond ionicities and metal-halogen vibrational frequencies are in harmony with corresponding data derived in an electrochemical environment, indicating that the metal-halogen bonding in vacuum share some features with the electrode metal surface-halogen bonding.

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Section: General Trends In the Adsorption Of Halogens On Cu Rh Pd Ag ...supporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

A Systematic Study of the Structure and Bonding of Halogens on Low-Index Transition Metal Surfaces

2006

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“…Additionally, formation of other compounds in the presence of oxidizing or reducing carrier gases is unlikely due to the strong interaction between iodine and silver and the thermal instability of compounds such as iodine oxides and hydroxides at the observed deposition temperatures. In an ab initio study on the chemisorption of halogens on the Ag(100) surface using an Ag 5 cluster as a model, a binding energy of − 187 kJ mol −1 was calculated for an iodine atom bound to such a cluster [20]. This indicates that the adsorption enthalpies observed in all conditions throughout the present study are compatible with chemisorption of iodine atoms on a silver surface.…”

Section: Resultssupporting

confidence: 57%

Silver as a capturing material for iodine released from lead–bismuth eutectic in various conditions

Karlsson

Neuhausen

Eichler

et al. 2021

J Radioanal Nucl Chem

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The usage of silver as a filtering material for removal of iodine from the gas phase of a lead–bismuth eutectic based nuclear reactor was investigated in various atmospheres representing normal operation as well as accident conditions. Thermochromatography experiments were performed to quantify the retention experienced on a silver surface by iodine species evaporated from a lead–bismuth eutectic sample. Measured adsorption enthalpies ranged from −171 to − 208 kJ mol−1 with observed differences attributed to various surface effects rather than a change in iodine speciation. The postulated adsorption mechanism is chemisorption of iodine atoms on the silver surface. Metallic silver fulfills the desired criteria for a capturing material in water-free filtering systems to be used as an alternative to traditional alkaline scrubbers commonly used in LWR systems.

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“…Illas et al, using the HF method with a cluster of five Ag atoms simulating the H 4 configuration of the Ag͑100͒ surface, obtained a value of 3.43 Å for the length of the BruAg bond. 20 Pacchioni 19 , also using the HF method with slightly larger clusters, found that the bond lengths between a Br ion and the surface Ag atom were 3.24 Å, 2.97 Å, and 2.94 Å in clusters of Br Ϫ -Ag 13 ͑mod-eling the H 4 structure͒, Br Ϫ -Ag 8 ͑simulating the B 2 geometry͒, and Br Ϫ -Ag 13 ͑representing the T 1 configuration͒, respectively. Ignaczak and Gomes 18 performed DFT calculations with clusters containing a Br ion and 12 metal atoms and determined the bond lengths to be 3.2 Å, 3.0 Å, and 2.9 Å for the H 4 , B 2 , and T 1 configurations of Br Ϫ -Ag 12 and Br Ϫ -Au 12 clusters, respectively.…”

Section: Relaxations and Energeticsmentioning

confidence: 98%

“…Several groups have performed ab initio Hartree-Fock ͑HF͒ and density-functional-theory ͑DFT͒ calculations for the Br/ Ag͑100͒ and Br/Au͑100͒ interfaces using cluster models. [17][18][19][20] While these investigations have provided useful information about the interaction between Br and the surfaces, as we discuss below, many of the results are not yet sufficiently accurate. For example, the preferred bonding site of Br on the Au͑100͒ surface was incorrectly predicted by ab initio DFT cluster calculations, which showed that Br would prefer to bond at the H 4 site on both the Ag͑100͒ and Au͑100͒ surfaces.…”

Section: Introductionmentioning

confidence: 96%

Ab initiocalculations for bromine adlayers on the Ag(100) and Au(100) surfaces: Thec(2×2)structure

Wang

Rikvold

2002

Phys. Rev. B

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Ab initio total-energy density-functional methods with supercell models have been employed to calculate the c(2ϫ2) structure of the Br-adsorbed Ag͑100͒ and Au͑100͒ surfaces. The atomic geometries of the surfaces and the preferred bonding sites of bromine have been determined. The bonding character of bromine with the substrates has also been studied by analyzing the electronic density of states and the charge transfer. The calculations show that while the fourfold hollow-site configuration is more stable than the twofold bridge-site topology on the Ag͑100͒ surface, bromine prefers the bridge site on the Au͑100͒ surface. The onefold on-top configuration is the least stable configuration on both surfaces. It is also observed that the second layer of the Ag substrate undergoes a small buckling as a consequence of the adsorption of Br. Our results provide a theoretical explanation for the experimental observations that the adsorption of bromine on the Ag͑100͒ and Au͑100͒ surfaces results in different bonding configurations.

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Vibrational frequencies of halogens adsorbed on Ag (100) based on ab initio cluster model calculations

Cited by 20 publications

References 15 publications

A Systematic Study of the Structure and Bonding of Halogens on Low-Index Transition Metal Surfaces

A Systematic Study of the Structure and Bonding of Halogens on Low-Index Transition Metal Surfaces

Silver as a capturing material for iodine released from lead–bismuth eutectic in various conditions

Ab initiocalculations for bromine adlayers on the Ag(100) and Au(100) surfaces: Thec(2×2)structure

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