77 research outputs found
Annular objective apertures improve resolution of electron microscopes
Hollow-cone illumination techniques, using an annular objective aperture located behind back focal plane of objective lens, increase image contrast and minimize chromatic aberrations
Direct observation of small cluster mobility and ripening
Direct evidence is reported for the simultaneous occurrence of Ostwald ripening and short-distance cluster mobility during annealing of discontinuous metal films on clean amorphous substrates. The annealing characteristics of very thin particulate deposits of silver on amorphized clean surfaces of single crystalline thin graphite substrates were studied by in-situ transmission electron microscopy (TEM) under controlled environmental conditions (residual gas pressure of 10 to the minus 9th power torr) in the temperature range from 25 to 450 C. Sputter cleaning of the substrate surface, metal deposition, and annealing were monitored by TEM observation. Pseudostereographic presentation of micrographs in different annealing stages, the observation of the annealing behavior at cast shadow edges, and measurements with an electronic image analyzing system were employed to aid the visual perception and the analysis of changes in deposit structure recorded during annealing. Slow Ostwald ripening was found to occur in the entire temperature range, but the overriding surface transport mechanism was short-distance cluster mobility
Electrode phenomena in high energy density discharges as applied to plasma acceleration problems
Electrode surface structure and morphology changes in high energy density discharges as applied to plasma acceleration problem
Study of electrode phenomena in high energy density discharges as applied to plasma acceleration problems second quarterly progress report
Electrode phenomena in high energy density discharges as applied to plasma acceleration problems - Low energy argon ion bombardment of thin, single, and polycrystals of gol
The Formation of Thin Continuous Films from Isolated Nuclei
Formation of thin continuous films from isolated nuclei and effect of electron beam, residual gases, and surface conditions on film growt
Impaired Collateral Recruitment and Outward Remodeling in Experimental Diabetes
OBJECTIVE—In this study, the effect of chronic hyperglycemia on acute ligation-induced collateral vasodilation, on monocyte chemotaxis, and on structural outward remodeling of collaterals was investigated
Surface Deposition and Imaging of Large Ag Clusters Formed in He Droplets
The utility of a continuous beam of He droplets for the assembly and surface
deposition of Ag clusters, ~ 300 - 6 000, is studied with transmission
electron microscopy. Images of the clusters on amorphous carbon substrates
obtained at short deposition times have provided for a measure of the size
distribution of the metal clusters. The average sizes of the deposited clusters
are in good agreement with an energy balance based estimate of Ag cluster
growth in He droplets. Measurements of the deposition rate indicate that upon
impact with the surface the He-embedded cluster is attached with high
probability. The stability of the deposited clusters on the substrate is
discussed.Comment: 24 pages, 5 figure
Estudo da sinterização de nanopartículas por microscopia eletrônica de transmissão in situ
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