Deposition of mass selected silver clusters in rare gas matrices

Abstract

We report on the successful ‘‘soft landing’’ of size selected silver dimers and trimers in solid krypton matrices. Silver cluster cations, produced by sputtering, were mass selected in a quadrupole mass filter and then codeposited with krypton on a cooled sapphire or CaF2 window in the presence of low energy electrons. Neutralized cluster samples were interrogated in situ by excitation and fluorescence spectroscopy. Deposition of slow (≤20 eV) silver dimer cations gave rise to strong excitation bands (centered at λ=275 and 390 nm) from Ag2 plus the characteristic triplet signal of the atom. The spectra imply that fewer than 25% of the dimers were fragmented during the neutralization and deposition steps. In similar experiments with Ag3 we were able to assign trimer absorption bands at 331, 364, 402, 421, 458, and 514 nm and identify characteristic emission features at 381, 560, and 626 nm.

Ultraviolet-visible absorption of small silver clusters in neon: Agn (n = 1–9)

“…In all cases the force matrix was calculated to ensure local minima in contrast to saddle points. Complete consistency has been found by comparing the lowest energy structures with previous results, 7, 9-16, 24 except for Ag 3 . In this case the b3-lyp functional fails to describe the geometry.…”

“…29 This multiplicity of site isomers is not observed in argon, nor in other matrices. 3,4 Ag 2 The experimental spectrum of Ag 2 in neon consists of four narrow peaks at 2.96, 4.68, 4.78, and 5.07 eV and an additional transition at 4.85 eV that appears as a shoulder. The small structures between 3.75 and 4.2 eV result from fragmentation and correspond to the Ag atomic absorption lines.…”

“…After deceleration the size selected cluster cations were deposited on a sample holder at low temperature together with a rare gas and neutralized to form a seeded rare gas matrix of neutral species. Using this technique Fedrigo et al [3][4][5] measured the optical absorption of silver neutral clusters at low temperature embedded in rare gas matrices (Ar, Kr, Xe). It was however not possible to measure the absorption spectra of Ag 4 , Ag 6 , Ag 10 , Ag 12 , Ag 14 clusters due to their low abundance in the molecular beam.…”

Structures and coalescence behavior of size-selected silicon nanoclusters studied by surface-plasmon-polariton enhanced Raman spectroscopy

“…Harbich, Lindsay and coworkers have reported that up to 75% of Ag 2 ϩ survive deposition at 30 eV. 22 As demonstrated in the cluster-surface collision experiments of St. John and Whetten, 49 fragmentation is even less likely for silicon clusters deposited at 25 eV, since they have higher dissociation energies and the larger clusters have correspondingly larger heat capacities. 3 In our experiments, evidence of fragmentation was only observed at the higher deposition energies.…”

“…19 Subsequently, DiCenzo, Berry and Hartford recorded photoemission spectra for size-selected gold clusters deposited on amorphous carbon. 20 Further photoemission studies on sizeselected clusters were performed by Eberhardt et al 21 Harbich, Lindsay and co-workers have done a number of studies on size-selected, matrix-isolated clusters, 22,23 while Jarrold and co-workers have done several experiments on sizeselected and deposited silicon clusters. [24][25][26] In a recent paper, Moskovits and co-workers identified the structure of Ag 5 deposited in an argon matrix using Raman spectroscopy.…”