Characterization of Nanoscale Particles Produced by Laser Vaporization / Condensation in a Diffusion Cloud Chamber

El‐Shall, M. Samy; Slack, W.; Hanley, D.; Kane, David B.

doi:10.1557/proc-351-369

Cited by 5 publications

(1 citation statement)

References 10 publications

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“…[8][9][10] It has different special functions, 11,12 and is a material that can be used in relation to heat, light, electricity, mechanics, and chemistry. Nano MgO can be prepared by many methods, although the solid, 13 liquid 14,15 and gas phase 16,17 methods are usually adopted. The solid phase method easily introduces impurities into the product.…”

Section: Introductionmentioning

confidence: 99%

Morphology and structure of nano MgO prepared by a novel nitrogen-protective pressurization method

et al. 2015

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A new micro stereoscopic structure of nano MgO was prepared by a novel nitrogen-protective pressurization method and characterized by SEM, EDS, and XRD. The nano MgO was formed by spherical units, and under the action of adsorption, the spherical units formed nanosheets by connecting to one another. Moreover, the units and sheets further gathered into laminations of nano MgO. The grain sizes of the nanosheet and laminate nano MgO were 11.8 nm and 367.6 nm, respectively, which were prepared by a novel method. The influence of nano MgO on morphology and structure were revealed by changing the amount of PVA, calcination time, and pressure.

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Section: Introductionmentioning

confidence: 99%

Morphology and structure of nano MgO prepared by a novel nitrogen-protective pressurization method

et al. 2015

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Synthesis of nanoparticles by reactive laser vaporization: silicon nanocrystals in polymers and properties of gallium and tungsten oxides

Li¹,

El‐Shall²

1998

Applied Surface Science

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Surface Oxidation and Luminescence Properties of Weblike Agglomeration of Silicon Nanocrystals Produced by a Laser Vaporization−Controlled Condensation Technique

1997

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Weblike aggregates of coalesced Si nanocrystals are produced by a laser vaporization-controlled condensation technique. SEM micrographs show particles with ∼10 nm diameter but the Raman shift suggests the presence of particles as small as ∼4 nm. FTIR of the freshly prepared particles shows weak peaks due to the stretching, bending, and rocking vibrations of the Si-O-Si bonds, indicating the presence of a surface oxidized layer, SiO x (x < 2). Further oxidation of the Si core appears to be very slow and inefficient under ambient temperature, but annealing at higher temperatures facilitates the oxidation. The particles show luminescence properties that are similar to those of porous Si and Si nanoparticles produced by other techniques. The nanoparticles do not luminesce unless, by exposure to air, they acquire the SiO x passivated coating. They show a short-lived blue emission characteristic of the SiO 2 coating and a biexponential longer-lived red emission. The short lifetime component of the red emission, about 12 µs, does not depend on emission wavelength. The longer-lived component has a lifetime that ranges from 80 to over 130 µs (at 300 K), increasing with emission wavelength. The results are consistent with the quantum confinement mechanism as the source of the red photoluminescence. IntroductionIn recent years, there has been an intense interest in the synthesis and characterization of nanoparticles. 1-8 Due to their finite small size, the nanoparticles often exhibit novel properties which are different from the bulk materials' properties. [1][2][3][4][5][6][7][8] Research in this area is motivated by the possibility of designing nanostructured materials that possess novel electronic, optical, magnetic, photochemical, and catalytic properties. Such materials are essential for technological advances in photonics, quantum electronics, nonlinear optics, and information storage and processing.Among the many interesting nanoparticles, silicon nanocrystals show important promise for use in Si-based devices for optical communication. This exciting possibility has been hampered by the indirect band gap of bulk Si which prevents efficient electron-photon energy conversion. However, the discovery that porous and nanocrystalline Si emit visible light with a high quantum yield has raised hopes for new photonic Si-based devices. 9-16 This discovery has also stimulated interest in the synthesis of Si nanocrystals which are believed to be the luminescent centers in porous silicon. 9,[17][18][19][20][21][22][23][24][25] Various methods have been used to make Si nanocrystals. They have been generated by the slow combustion of silane, 26 reduction of SiCl 4 by Na, 27 separation from porous Si, 28 UV or IR laser photolysis of silane-type precursors, 29 thermal evaporation, 30 microwave discharge, 31 RF sputtering, 32 and hightemperature aerosol techniques. 18 In most cases, some control over particle size can be achieved by lowering the concentration of the nucleating particles. Laser vaporization of metals has the advantage ...

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Characterization of Nanoscale Particles Produced by Laser Vaporization / Condensation in a Diffusion Cloud Chamber

Cited by 5 publications

References 10 publications

Morphology and structure of nano MgO prepared by a novel nitrogen-protective pressurization method

Morphology and structure of nano MgO prepared by a novel nitrogen-protective pressurization method

Synthesis of nanoparticles by reactive laser vaporization: silicon nanocrystals in polymers and properties of gallium and tungsten oxides

Surface Oxidation and Luminescence Properties of Weblike Agglomeration of Silicon Nanocrystals Produced by a Laser Vaporization−Controlled Condensation Technique

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