Borisenko L.A.1 , Malikova A.S.1 , Image-processing of low-density metal nanoparticle layers (Bi) from the X-Ray tomograph SkyScan-1074 Borisenko L.A.1 , Malikova A.S.1 , Orekhov A.S.2 1 Lomonosov Moscow State University, Physical Faculty, Moscow, Russia 2LPI of Russian Academy of Science, Moscow, Russia Email: borisenko.lidiya@physics.msu.ru malikova.anastasiya@physics.msu.ru orekhov@sci.lebedev.ru

A washer with the target . Target scheme in the laser-plasma experiment. Targets for laser-plasma experiments. SEM-image of the M-layer (scale bar 100 mkm).

SEM-image of Cu nanoparticle layer of 0 SEM-image of Cu nanoparticle layer of 0.1 g/cm3 density (scale bar 2 mkm). Normal density Bi “wedge” 1, 2 and 3 mkm thick(used to calculate absorption coefficient). Graphite cylinders (“witnesses”) with Bi layer obtained by vapor deposition under the same circumstances, as the targets. Set-up scheme: 1 –vacuum vessel, 2 - bottom, 3 –vacuum and gas pumps, 4 – vessel with heated metal, 5 – heat shield, 6 – targets, 7 – “witness”.

The X-Ray tomograph SkyScan-1074. Voltage in the X-Ray tube 40 kV; Current in the tube 1000 mA; Field of vision 16x20 mm; Definition 21.2 mkm/pixel; Dynamical range 12 bit. A. Orekhov on SkyScan-1074. The rotary table with a sample (“witness”) and the detector (on the left). “Witnesses” – graphite cylinders with metal nanoparticle layer - in color gradient: more absorbing Bi layer on the top in green.

The “witness” graphite cylinder before vapor deposition and the corresponding blackening profiles (averaged over 1, 3 and 5 pixels and theoretical curve in black).

Data for the “hat”. Data for graphite cylinder. Graphite Ø 0.7 mm. The “witness” with thick (~140 mkm) Bi layer on the top (the “hat”) and corresponding blackening profiles (horizontal on the right and vertical on the top).

Data for the “hat”. Data for graphite cylinder. Graphite Ø 0.7 mm. The “witness” with thin (~70 mkm) Bi layer on the top (the “hat”) and corresponding blackening profiles (horizontal on the right and vertical on the top).

Elliptical approximation for the left half of the “hat” of the “witness”, density and thickness calculations for both left and right halves of the “hat”.

Data-processing for the cylindrical side layers on the “witnesses”. “Witnesses” with thick (on the top) and thin Bi layers. Logarithmical fit for the side Bi layer densities (from the outer layer to graphite).

Comparison of the left and right sides of the “witness” Comparison of the left and right sides of the “witness”. Radial asymmetry for the sample with thick Bi layer. Due to side-position of the samples in the set-up varying thickness and density (mostly in the outer layers) for the left and right sides of the cylinder appear.

Conclusions and results. The non-destructive method of low-density metal nanoparticle targets characterization was developed – X-Ray microtomography on SkyScan-1074 of the “witnesses” – specially created cylindrical objects with the same metal layer, as on the target. The notion of partially filled CCD-matrix pixel was introduced which made possible to exclude extra-low density of the outer layers. It was shown that the outer layers have densities 2-3 times lower then the inner layers due to the specificity of the metal nanoparticle layer-growth process. The outer layer is a bit asymmetrical which may be because of the cylinder’s slope or a light gas flow in the set-up during the initial vapor deposition period. First versions of computer programs for layer characterization were created (with the possibility to calculate density gradient from graphite to the outer layers and the total absolute thickness of the sample, for both elliptical and cylindrical layers). The programs were tested on several specially prepared objects (cylinders and tubes) made of solid materials which proved the idea of partially filled CCD-matrix pixel. The programs created were used to characterize low-density metal nanoparticle targets. This resulted in reduced time to calculate the necessary characteristics (total thickness and average density) from experimental image.

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