Effect of interface on structural fluctuation in gold clusters fixed on MgO fine rods

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.

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“…17 Kizuka and co-workers have also found it in fluctuating structures. 32 Such spherical decahedral structures FIG. 7.…”

Section: Discussionmentioning

confidence: 99%

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

Koga¹,

Hattori²,

Ikeda

et al. 1998

Phys. Rev. B

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“…This ͑001͒ TiN ʈ ͑001͒ Au epitaxial relation is similar to that observed for gold clusters deposited on the MgO ͑001͒ surface from both high-resolution electron microscopy experiments and MD simulations. [25][26][27][28] On the other hand, it is worth to note that there is a misfit between the Au and TiN lattices, being the Au cell parameter somewhat lower ͑a = 4.078 and 4.254 Å, respectively͒. This misfit mainly affects the first layer of gold atoms, which is found to be slightly stressed, however, beyond this layer; the Au cluster gradually contracts to recover the metallic structure.…”

Section: MD Simulations Of Au Clusters Deposited On Tin "001… Surmentioning

confidence: 90%

Interaction potentials from periodic density-functional theory calculations: Molecular-dynamics simulations of Au clusters deposited on the TiN (001) surface

Hernández

Sanz

2005

The Journal of Chemical Physics

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Molecular-dynamics simulations of gold particles deposited on a TiN (001) surface have been accounted for through classical pair potentials describing the atom force field. The interaction between Ti-N, Ti-Ti, N-N, Au-Au, Au-Ti, and Au-N pairs was estimated by following a procedure in which the interaction energy between two sets of atoms is estimated from density-functional calculations performed with periodic boundary conditions using plane waves as basis set. The pair potentials were expressed as the sum of two contributions: long range in a Coulomb form and a short-range term, which included the rest of the energy contributions. Simulations of the TiN (001) isolated surface reproduced the already described surface relaxation, with a rippling parameter in agreement with that found from a purely first-principles approach. Simulations of gold deposition on such surfaces showed the formation of metal clusters with well-defined fcc structure and epitaxially grown.

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“…A silicon integrated target camera (LHESA: LH-4036) and a S-VHS tape recorder with a digital frame memory were employed for dynamic observation in addition to conventional film recording system (Kizuka ct al. 1993, Kizuka et a/. 1994.…”

Section: Processing and Observation In The High-resolution Transmissimentioning

confidence: 97%

“…In addition, structural changes can be observed dynamically at atomic resolution (Kizuka, Kachi andTanaka 1993, Kizuka andTanaka 1994).…”

mentioning

confidence: 99%

Nanometre scale electron beam processing andin situatomic observation of vacuum-deposited MgO films in high-resolution transmission electron microscopy

Kizuka

Tanaka

1995

Philosophical Magazine A

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Nanometre scale processing was performed on vacuum-deposited single crystalline magnesium oxide films by using a nanometre-sized electron beam in highresolution transmission electron microscopy (HRTEM). Two kinds of processing, drilling and edge-flattening, were demonstrated. The resolution of the present processing was demonstrated by the minimum size of the hole being about 4 nm and the minimum distance between holes being 14nm. The shape modulation during the processing was observed for the first time in situ dynamically,at atomic resolution. The dynamic observations in HRTEM showed that the processing is caused by desorption of constituent atoms from the solid state surface of the magnesium oxide films. It was found that the size of the processing area could be controlled at the atomic scale by adjusting the irradiation time during the in situ observation of the processing. 1. INTRODUCTIONVarious kinds of nanometre scale processing are required to be applied to advanced materials. Materials which need to be processed and artificially modified at the atomic scale, are exemplified by the semiconductor (Esaki and Tsu 1970), metal (Grunberg, Shreiber, Pang, Brodsky and Sowers 1986) and ceramic (Shigematsu, Ushigome, Bando and Takada 1980) superlattices, and nanometre-grained polycrystalline materials (Birringer 1989). Recently, electron beam processing at the nanometre scale (by drilling, line-writing and structure-modification due to the direct irradiation effect and the electron stimulated chemical reaction) has been attempted using scanning transmission electron microscopy (STEM) (Mochel, Humphreys, Eades, Mochel and Petford 1983, Muray, Scheinfein, Isaacson and Adesida 1985, Macaulay and Berger 1987, Turner, Bullough, Devenish, Maher and Humphreys 1990, Pan and Broers 1992, Chen, Boothroyd and Humphreys 1993. These studies have focused on the improvement of the processing resolution and the evaluation of the suitability of some irradiation-sensitive materials for electron beam processing. The minimum size of the processed area was 1 nm for MgO smoke particles (Turner et al. 1990), and 2 nm for p-alumina (Mochel et al. 1983) and SiO, (Chen et al. 1993); the minimum line width was 5 nm and the minimum distance between the lines was 17 nm for AIF, (Macaulay et al. 1987, Macaulay, Allen, Brown andBerger 1989) during direct electron beam processing. Areas 2 nm in diameter separated by 4 nm in AlF, (Muray et al. 1985) and lines of 10 nm width and 15 nm pitch in SiO, (Pan and Broers 1992) were processed using a chemical reaction in addition to the direct electron 0141-8610/95 $10~00 0 1995 Taylor

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Effect of interface on structural fluctuation in gold clusters fixed on MgO fine rods

Cited by 23 publications

References 13 publications

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

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

Interaction potentials from periodic density-functional theory calculations: Molecular-dynamics simulations of Au clusters deposited on the TiN (001) surface

Nanometre scale electron beam processing andin situatomic observation of vacuum-deposited MgO films in high-resolution transmission electron microscopy

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