Models for statistical decomposition of metal clusters: Vibrational frequency distributions

Shvartsburg, Alexandre A.; Ervin, Kent M.; Frederick, John H.

doi:10.1063/1.471595

Cited by 42 publications

(39 citation statements)

References 49 publications

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“…͑2͒ and ͑10͒ in Rodgers et al 22 ͔. The vibrational and rotational frequencies required to calculate the internal energy distribution and the RRKM dissociation rates are estimated from surface science measurements, ab initio calculations, and empirical models [23][24][25][26][27] and are listed in Table I. Finally, Eq. ͑4͒ is convoluted over the thermal velocity distribution of the target gas and the measured energy distribution of the reactant ions.…”

Section: Results and Threshold Analysismentioning

confidence: 99%

Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Spasov

Ervin

1998

The Journal of Chemical Physics

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Articles you may be interested inStability of small Pd n ( n = 1 -7 ) clusters on the basis of structural and electronic properties: A density functional approach Measurement of the dissociation energies of anionic silver clusters ( Ag n − , n=2-11) by collision-induced dissociation J. Chem. Phys. 110, 5208 (1999); 10.1063/1.478416 Erratum: "Ligand and metal binding energies in platinum carbonyl cluster anions: Collision-induced dissociation of Pt m − and Pt m (CO) n " [J. Ligand and metal binding energies in platinum carbonyl cluster anions: Collision-induced dissociation of Pt m − and Pt m ( CO ) n − The bond dissociation energies of palladium trimer anion, Pd 3Ϫ , and its carbonyls, Pd 3 ͑CO͒ n Ϫ (n ϭ1 -6), are measured in the gas phase by the energy-resolved collision-induced dissociation method. The values obtained are D 0 (Pd 2 Ϫ ϪPd)ϭ2.26Ϯ0.36 eV for the bare cluster and D 0 (Pd 3 ͑CO͒ nϪ1Ϫ ϪCO)ϭ1.78Ϯ0.32 eV, 1.74Ϯ0.22 eV, 1.47Ϯ0.22 eV, 1.13Ϯ0.15 eV, 1.11 Ϯ0.15 eV, and 1.14Ϯ0.17 eV for nϭ1 -6, respectively, for the carbonyls. The results show a general decrease of the bond energy with an increasing number of carbonyls, with two relatively stable structures, Pd 3 ͑CO͒ 2 Ϫ and Pd 3 ͑CO͒ 6 Ϫ . A symmetric Pd 3 ͑CO͒ 2 Ϫ structure with two three-fold bridged carbonyls is postulated.

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Section: Results and Threshold Analysismentioning

confidence: 99%

Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Spasov

Ervin

1998

The Journal of Chemical Physics

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“…47 As input for the RRKM analysis, the frequencies of the Pt clusters are approximated by a discrete Debye model. 48 As an example Fig. 4 shows the dependence of k d on the CO chemisorption energy for Pt 13 •(CO) k and Pt 18 •(CO) k with k = 1, 2.…”

Section: Statistical Modelling Of the Reactionmentioning

confidence: 99%

Tolerance of platinum clusters to CO poisoning induced by molybdenum doping

Kaydashev

Janssens

Lievens

2015

International Journal of Mass Spectrometry

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Please cite this article as: V. Kaydashev, Tolerance of platinum clusters to CO poisoning induced by molybdenum doping, International Journal of Mass Spectrometry (2015), http://dx. ABSTRACTThe influence of a single Mo dopant atom on the CO adsorption on isolated cationic platinum clusters in the gas phase, Pt n + (13 ≤ n ≤ 24), has been investigated. The sticking probability of the first CO molecule to bare Pt n + clusters is estimated to be close to unity and is not notably changed upon Mo doping. The adsorption probability of the second CO molecule, however, shows a significant reduction for Pt n−1 Mo + compared to Pt n + , reaching a maximal reduction of as much as 80% for Pt 19 Mo + . As a result, the average number of CO molecules adsorbed on Pt n + with 19 ≤ n ≤ 24, and surviving on the time scale of the experiment, decreases by about 10−15% upon substitution of a single Pt atom by a single Mo atom. A statistical analysis of the unimolecular dissociation of the clusterCO complexes suggests that the lower sticking probability for the second CO molecule for Mo-doped species is related to a reduction of the CO chemisorption energy. Electron transfer from Mo to Pt resulting in a lowering of the Pt 5dvacancies and a downshift of the 5d-center is likely responsible for this reduced CO binding energy.

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“…However, the effect of vibrational frequencies on the effective temperatures is not as strong as that of size, for physically reasonable varia- tions. Anharmonicity effects tend to mimic lower frequencies [51].…”

Section: Size Dependencementioning

confidence: 99%

Microcanonical analysis of the kinetic method. The meaning of the “apparent entropy”

Ervin

2002

J. Am. Soc. Mass Spectrom.

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135

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A rigorous analysis of the kinetic method is carried out using Rice-Ramsperger-KasselMarcus (RRKM) theory of microcanonical statistical unimolecular dissociation rates. The model employs a kinetics treatment appropriate for metastable ion dissociation. Protonbound alkoxide dimer anions are used as model systems, with realistic vibrational and rotational parameters calculated by ab initio methods for the cluster ion and transition states leading to the competitive dissociation channels. The numerical simulations show that the kinetic method plots of ln(I 2 /I 1 ) versus ⌬⌬H are nearly linear but can exhibit significant curvature. The apparent entropy obtained in the extended kinetic method is not approximately equal to the thermodynamic entropy difference for dissociation, ⌬⌬S(T), or for activation, ⌬⌬S ‡ (T), either at the effective temperature or at any fixed equilibrium temperature. Instead, the apparent entropy term can be related to the ratio of the microcanonical sum of states of the dissociation transition states for the kinetically selected internal energy of the dissociating ions. (J Am Soc Mass Spectrom 2002, 13, 435-452)

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Models for statistical decomposition of metal clusters: Vibrational frequency distributions

Cited by 42 publications

References 49 publications

Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

Tolerance of platinum clusters to CO poisoning induced by molybdenum doping

Microcanonical analysis of the kinetic method. The meaning of the “apparent entropy”

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