In situgrazing-incidence x-ray-diffraction and electron-microscopic studies of small gold clusters

Abstract

Small gold clusters having diameters of 1-3 nm have been studied by using x-ray-diffraction and electron microscopy. Large amounts of small gold clusters generated by the inert-gas vapor-condensation method were deposited on a silicon wafer cooled down to 92 K to avoid coalescence growth and grazing-incidence x-raydiffraction intensity from the cold cluster deposit was measured in situ. The diffraction pattern was analyzed and compared quantitatively with calculated patterns from several structural models considering the observed size distribution and found to be explainable approximately by a decahedral structure with geometrically closed shells. Electron-microscopic observations for gold clusters deposited sparsely on an amorphous carbon film at room temperature were also performed and decahedral multiply-twinned clusters 2-3 nm in diameter were frequently observed. This result agrees well with the x-ray statistical result, suggesting that the most dominant structure of small gold clusters prepared under our experimental conditions is the decahedral structure. The present experiments have demonstrated that an extremely weak x-ray-diffraction signal from such a small cluster can be measured quantitatively by preparing a cold cluster deposit.

Global minima of AlN, AuNand PtN,N⩽ 80, clusters described by the Voter–Chen version of embedded-atom potentials

“…Structural characterization using a variety of experimental techniques can be performed on Au clusters [62,63,64,65,66]. Experiments suggest that gold nanoclusters with diameters of 1-2 nm, corresponding to aggregates with N=20-200 atoms, are amorphous [62,63].…”

Density-functional study ofAun(n=2–20)clusters: Lowest-energy structures and electronic properties

“…Gold clusters are currently attracting interest as the building blocks of novel nanostructured materials and devices. [1][2][3][4] During the past two decades, the structures of gold clusters have been studied both experimentally [5][6][7][8][9][10] and theoretically. [11][12][13][14][15][16][17][18][19][20][21][22] Experiments suggest that gold nanoclusters with diameters of 1 − 2 nm are amorphous.…”

Structure and atoms mixing in electrodeposited Sn(Au) nanoaggregates

“…The Au lattice parameters for this deposit (a ¼ 0:4080 nm) are in agreement with the bulk gold material value. It shows that the 2 nm gold deposit is well crystallized and presents no lattice relaxation as observed in smaller aggregates [15]. The intensity ratio analysis reveals no preferential orientation.…”