Narrow size-distributed silicon cluster beam generated using a spatiotemporal confined cluster source

Iwata, Yasushi; Kishida, Masaaki; Muto, Makiko; Yu, Shengwen; Sawada, Tsuguo; Fukuda, Akira; Takiya, Toshio; Komura, Akio; Nakajima, Kimiko

doi:10.1016/s0009-2614(02)00556-0

Cited by 16 publications

(9 citation statements)

References 15 publications

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“…It is possible to use the shock wave to rapidly change the state quantity in the plume and increase the supersaturation at a fast rate. One example is the laser ablation process done in a closed space such as an ellipsoidal cell, in which the collision between the reflected shock wave and the plume front triggers the formation of nanoparticles instantly in a small area [43,44]. The equipment fabricating monodispersed nanoparticles by using this phenomenon is called Spatiotemporal Confined Nanoparticle Source (SCCS), which is illustrated in Figure 6 [45], as the fabrication process is restrained in the confined space and time.…”

Section: The Direct Fabrication Of Monodisperse Nanoparticlesmentioning

confidence: 99%

Nanoparticle Formation and Deposition by Pulsed Laser Ablation

Takiya¹,

Fukuda²

2021

Practical Applications of Laser Ablation

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Pulsed Laser Ablation (PLA) in background gas is a good technique to acquire specific nanoparticles under strong non-equilibrium states. Here, after a history of PLA is mentioned, the application of nanoparticles and its deposition films to the several fields will be described. On the target surface heated with PLA, a Knudsen layer is formed around the adjacent region of the surface, and high-pressure and high-temperature vapor atoms are generated. The plume formed by evaporated atoms blasts off with very high-speed and expands rapidly with a shock wave. A supercooling phenomenon occurs during this process, and number of nucleus of nanoparticle forms in vapor-phase. The nuclei grow by the condensation of vapor atoms and deposit on a substrate as nanoparticle film. If the radius of nanoparticle is uniformized, a self-ordering formation can be shown as a result of interactive process between each nanoparticle of the same size on the substrate. In this chapter, the related technology to realize a series of these processes will be expounded.

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Section: The Direct Fabrication Of Monodisperse Nanoparticlesmentioning

confidence: 99%

Nanoparticle Formation and Deposition by Pulsed Laser Ablation

Takiya¹,

Fukuda²

2021

Practical Applications of Laser Ablation

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“…Silicon clusters were then generated in the mixed gas-phase layer, which was confined in a narrow space with a thickness smaller than 1.0 mm. Confinement of the mixed gas-phase layer, such that it lasted for a much shorter time (150−200 μs) 32 than the time scale of diffusion (1 ms typical), allowed for uniform regulation of the thermodynamically adiabatic conditions; these are necessary to control the silicon cluster growth with a monodispersive cluster-size distribution. A group of silicon clusters, effusing from the exit of the cell into a vacuum, formed a pulsed neutral beam after passing through a skimmer; this was introduced into a synthesis chamber in a high vacuum (below 1 × 10 −7 Pa).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…A spherical shock wave, centered at the focal point on the target surface, was propagated and reflected on the wall of the cell; it was then focused on the other focal point near the exit of the cell . The reflected shock wave collided with the silicon vapor front traveling forward along the center axis of the cell; the silicon vapor front was stalled near the focal point. , A thinner part of the hot silicon vapor front mixed with helium at liquid-nitrogen temperature; a dense mixed gas-phase layer was formed at the contact area of both gases. Silicon clusters were then generated in the mixed gas-phase layer, which was confined in a narrow space with a thickness smaller than 1.0 mm.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…In this study, the crystallographic coalescence into silicon cluster superlattice structures has been investigated with the use of a new laser ablation-type silicon cluster beam system. This system, which is based on a principle that has been theoretically − and empirically developed, can control the growth of the silicon clusters by shock-wave confinement to obtain a highly condensed pulsed beam with a uniform size distribution. Absolute values of the crystallographic structures of the silicon cluster superlattices formed on a graphene substrate were also studied and discussed to describe the crystallographic coalescence into the superlattice structure.…”

Section: Introductionmentioning

confidence: 99%

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Crystallographic Coalescence of Crystalline Silicon Clusters into Superlattice Structures

Iwata¹,

Tomita²,

Uchida

et al. 2015

Crystal Growth & Design

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The crystallographic coalescence of crystalline silicon clusters into superlattice structures, generated by direct deposition of a silicon cluster beam on a graphene substrate, has been observed. High-resolution transmission electron microscopy and transmission electron diffraction analyses revealed that adjacent silicon clusters in the superlattices, having a mean diameter of 1.61 ± 0.05 nm (n = 109, n indicating the cluster size, Si n ) and an sp 3 diamond structure, form sp 3 covalent bonds between Si atoms on their surfaces and align their atomic crystalline axes, forming crystallographic rows to coalesce into bcc superlattice structures with a lattice constant of 2.134 ± 0.002 nm. The hcp configuration of the silicon clusters with the same lattice constant as the bcc superlattice unit cell is commensurate with the crystallographic structure of the graphene substrate. The absorption spectra confirm the sp 3 diamond structure of the silicon clusters under well-quantized conditions. Oxygen-free unoccupied electronic states (UDOS) in the conduction band of the silicon cluster superlattices appeared at 99.8 eV in the electron energy loss spectroscopy spectra. The s + d UDOS at 107.5 eV in SiO 2 became conspicuous as the oxidation of the specimen advanced. The collective bulk plasmon loss of the virtually oxygen-free silicon cluster superlattice appeared at 16.7 eV.

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“…On the other hand, there is a method of making the best size at the stage of the generation of the cluster. The method of using an axisymmetric elliptical cell and the shock wave is proposed to this [2]. This method makes use of interaction phenomena between the plume and shock wave arising in elliptical cell following laser ablation in inert gas.…”

Section: Introductionmentioning

confidence: 99%

Behavior of shock waves formed by unsteady supersonic jet injected into cell

et al. 2008

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The unsteady behavior of flow driven by a jet suddenly injected into a cell is numerically studied by solving the axisymmetric two-dimensional compressible Navier-Stokes equations. The system of the calculation is a model of the laser ablation of a certain duration followed by a discharging process through the exit hole at the downstream end of the cell. In the calculations, the contour of the cell is changed while other parameters such as the Mach number of the jet, its duration, and the diameter of the cell exit are fixed. Monitoring the velocity at the exit hole is used to investigate the influence of the shape on the interaction between the shock wave and the jet.As the result, it was found that the velocity peak value and its arrival time at the downstream end of the cell exit are determined by the diameter of the cell.

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Narrow size-distributed silicon cluster beam generated using a spatiotemporal confined cluster source

Cited by 16 publications

References 15 publications

Nanoparticle Formation and Deposition by Pulsed Laser Ablation

Nanoparticle Formation and Deposition by Pulsed Laser Ablation

Crystallographic Coalescence of Crystalline Silicon Clusters into Superlattice Structures

Behavior of shock waves formed by unsteady supersonic jet injected into cell

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