Chemical and Catalytic Properties of Size-Selected Free and Supported Clusters

Bernhardt, Thorsten M.; Heiz, Ulrich; Landman, Uzi

doi:10.1007/978-3-540-32646-5_1

Cited by 67 publications

(70 citation statements)

References 431 publications

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“…1,2 The oxidation processes of Pd surfaces have been extensively studied for model catalyst systems. 3 The interaction between oxygen (O 2 ) and the Pd surface is complex and not well-understood at present.…”

Section: Introductionmentioning

confidence: 99%

Release of Oxygen from Palladium Oxide Cluster Ions by Heat

Miyajima

Mafuné

2015

J. Phys. Chem. A

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Palladium oxide cluster ions, PdnOm(+), were prepared in the gas phase using laser ablation of a palladium rod in the presence of oxygen. The cluster ions were heated to 1000 K downstream from the cluster source (post heating), and the abundance of PdnOm(+) (n = 2-7) was examined using mass spectrometry. Temperature-programmed desorption experiments revealed that an oxygen molecule is released from oxygen-rich PdnOm(+), forming oxygen-deficient PdnOm-2(+). It was found that Pd6O4(+) was thermally stable up to 1000 K. The activation energy for oxygen molecule desorption has been obtained and compared with previous results by Lang et al.

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Section: Introductionmentioning

confidence: 99%

Release of Oxygen from Palladium Oxide Cluster Ions by Heat

Miyajima

Mafuné

2015

J. Phys. Chem. A

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“…22 The thermochemistry of MnO2 is known to However, a limited number of experimental and theoretical studies have been proposed on the gas-phase or unsupported manganese oxide clusters. [29][30][31] Ziemann et al produced manganese oxide clusters by a gas-aggregation technique and observed the formation of (MnO)x + (x = 1-13) and (MnO)xO + (x = [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] clusters by photoionization at 248 nm; 29 the mass-spectral abundance distribution suggested that the most stable structures for the stoichiometric clusters are stacks of rings of (MnO)3 units and that the oxygen-rich clusters prefer structures with a single Mn atom vacancy. Yin et al studied the reactivity of neutral manganese oxide clusters MnnOm (n = 2-13), which were generated by laser ablation of a Mn foil into 5% O2/He carrier gas and photoionized by a 118-nm laser radiation.…”

Section: Introductionmentioning

confidence: 99%

Stable Stoichiometry of Gas-Phase Manganese Oxide Cluster Ions Revealed by Temperature-Programmed Desorption

et al. 2015

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Temperature-programmed desorption (TPD) experiments were performed on gas-phase manganese oxide cluster ions, namely, Mn(n)O(m)(+) (n = 3-20) and Mn(n)O(m)(-) (n = 3-18). These cluster ions were prepared by laser ablation of a manganese rod in the presence of oxygen gas, and their composition was investigated using mass spectrometry. The composition of Mn(n)O(m)(±) distribution lies above the m = (4/3)n line. When the cluster ions were heated to 1000 K, Mn(n)O(m)(+) (m = (4/3)n + δ, with δ = -1, 0) and Mn(n)O(m)(-) (m = (4/3)n + δ, with δ = 0, 1) was found to be the predominant species, formed by thermal dissociation. These experimental findings indicate that the nascent manganese oxide clusters comprise robust Mn(n)O(m)(±) (m/n ≈ 4/3) and weakly bound excess oxygen atoms. On the basis of the TPD experiments, the oxygen-molecule release was identified as the main dissociation channel. The temperature dependence of O2 desorption was found to be similar among the clusters with the same oxygen excess or deficiency regardless of the number of Mn atoms. The threshold energy of O2 desorption was estimated for Mn4O(m)(+) (m = 6-11) and compared with bond dissociation energies calculated by density functional theory.

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“…This can be achieved directly by means of space-resolved tunneling spectroscopy (scanning tunneling spectroscopy, STS), as it gives a space-and energy-resolved local density of electronic states of individual clusters. By means of this powerful technique, several research groups have elucidated the localized nature of electrons of clusters prepared on solid surfaces by mapping the local density of electronic states at a given energy [1][2][3][4][5][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Bollinger et al have reported that metallic edge states are localized at a periphery of a monatomic-layered MoS 2 cluster having a diameter of $5 nm prepared on a reconstructed Au(1 1 1) surface [11].…”

Section: Introductionmentioning

confidence: 99%

“…One of the characteristics to tackle this issue is a HOMO-LUMO gap (an energy gap between the highest occupied and the lowest unoccupied molecular orbitals) [1][2][3][4][5] like the band gap of solid materials. For instance, the HOMO-LUMO gap of supported clusters of metal and semiconductor atoms has been reviewed by Sattler [4].…”

Section: Introductionmentioning

confidence: 99%