Fluorescence microscopy and spectroscopy of subsurface layer dynamics of polymers with nanometer resolution in the axial direction

2015 ◽  
Vol 184 ◽  
pp. 237-249 ◽  
Author(s):  
Yuri G. Vainer ◽  
Yaroslav I. Sobolev ◽  
Andrei V. Naumov ◽  
Igor S. Osad'ko ◽  
Lothar Kador
Keyword(s):  
Vapor Deposition ◽  
Amorphous Polymer ◽  
Subsurface Layer ◽  
Polymer Surface ◽  
Axial Direction ◽  
Controlled Diffusion ◽  
Subsurface Layers ◽  
20 Nm ◽  
Physical Reasons ◽  
Fluorescent Molecules

We studied the dynamics in ultrathin subsurface layers of an amorphous polymer by the spectra of single fluorescent molecules embedded into the layer by vapor deposition and subsequent controlled diffusion to the desired depth in ≈0.5 nm steps. The spectral trails of single molecules were recorded at 4.5 K as a function of diffusion depth. In depths shallower than 20 nm, the spectral dynamics deviate from those deep in the bulk. Less than 5 nm deep, the linewidths increase rapidly, whereas the number of detected molecules decreases. No zero-phonon lines were observed closer than 0.5 nm to the polymer surface. Possible physical reasons of the observed phenomena are discussed.

Interactions of surface drying and subsurface nutrients affecting plant growth on acidic soil profiles from an old pasture

1986 ◽  
Vol 26 (6) ◽  
pp. 681 ◽  
Author(s):  
A Pinkerton ◽  
JR Simpson
Keyword(s):  
Subsurface Layer ◽  
Acid Soils ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Soil Profiles ◽  
Poor Growth ◽  
South Wales ◽  
Reconstituted Soil ◽  
Subsurface Layers ◽  
Surface Drying

Previous studies on soils from old pastures in southern New South Wales have demonstrated that nutrients have accumulated at the soil surface, but that the 40-100-mm depth layer in many profiles has become strongly acidic (e.g. pH 4.7), and high in extractable aluminium. Poor growth of subterranean clover has occurred on such soils during dry periods and may be associated with poor root growth in the acidic, nutrient-poor subsurface layers. Possible nutritional causes of these observations were investigated using reconstituted soil profiles. The root and shoot growth of subterranean clover, wheat, oats and lucerne were compared in unamended profiles and in profiles amended by applying nutrients or calcium carbonate (lime) to correct the more obvious deficiencies of the subsurface layers. Subterranean clover grew well as long as the surface soil remained moist, so that plants could utilise the nutrients potentially available within it. When the surface (0-40 mm) was allowed to dry but the subsurface layers remained moist, growth was poor unless phosphate was applied to the moist layer. Subsurface application of lime alone was ineffective. Nitrogen application increased clover growth in the presence of added phosphate or surface moisture, but nitrogen alone did little to alleviate the effects of surface drought. Wheat, and to a lesser extent oats, responded to subsurface lime when the surface was moist, and both responded to subsurface phosphate when the surface was dry. Lucerne responded to subsurface phosphate similarly to subterranean clover but the response was more than doubled in the presence of additional borate and lime. Lime without borate was not effective. When the surface was maintained moist, liming both the surface (0-40 mm) and subsurface layers improved the response over liming the subsurface layer only. The results suggest that declining fertility and productivity in old pastures developed on acid soils may not be rectified by liming alone, but that cultivation, ripping or drilling of phosphate, and in some cases addition of borate, may be required to improve the penetration of nutrients, particularly phosphorus, to greater depth.

A Simple Approach to Recognize Axial Direction of ReS2 Single Crystals Grown by Chemical Vapor Deposition

2018 ◽  
Vol 255 (8) ◽  
pp. 1800142 ◽  
Author(s):  
Peng Chen ◽  
Jianyu Wang ◽  
Yan Lu ◽  
Sihong Zhang ◽  
Zhendong Wang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Single Crystals ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Axial Direction ◽  
Simple Approach

Comparison of Aluminum Nitride Nanowire Growth with and without Catalysts via Chemical Vapor Deposition

2011 ◽  
Vol 1324 ◽  
Author(s):  
Kasif Teker ◽  
Joseph A. Oxenham
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Systematic Investigation ◽  
Efficient Catalyst ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Direct Nitridation ◽  
20 Nm

ABSTRACTThis paper presents a systematic investigation of AlN nanowire synthesis by chemical vapor deposition using Al and NH3 on SiO2/Si substrate and direct nitridation of mixture of Al-Al2O3 by NH3. A wide variety of catalyst materials, in both discrete nanoparticle and thin film forms, have been used (Co, Au, Ni, and Fe). The growth runs have been carried out at temperatures between 800 and 1100oC mainly under H2 as carrier gas. It was found that the most efficient catalyst in terms of nanowire formation yield was 20-nm Ni film. The AlN nanowire diameters are about 20-30 nm, about the same thickness as the Ni-film. Further studies of direct nitridation of mixture of Al-Al2O3 by NH3 have resulted in high density one-dimensional nanostructure networks at 1100oC. It was observed that catalyst-free nanostructures resulted from the direct nitridation were significantly longer than that with catalysts. The analysis of the grown nanowires has been carried out by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and x-ray diffraction.

Effect of high-power ion beams on the surface topography and structure of submicrocrystalline titanium alloy subsurface layers

2018 ◽  
pp. 82-91
Author(s):  
M. V. Zhidkov ◽  
A. E. Ligachev ◽  
Yu. R. Kolobov ◽  
G. V. Potemkin ◽  
G. E. Remnev
Keyword(s):  
Grain Size ◽  
Titanium Alloy ◽  
High Power ◽  
Ion Beam ◽  
Structural Phase ◽  
Subsurface Layer ◽  
Ion Beams ◽  
Uniform Structure ◽  
Average Grain Size ◽  
Subsurface Layers

The study covers the topography and structural phase state of VT1-0 and VT6 submicrocrystalline titanium alloy subsurface layers irradiated by high power pulsed carbon ion beams (ion energy is 250 keV, pulse duration is ~100 ns, pulse current density is 150–200 A/cm2; surface energy density of a single pulse is j ~ 3 J/cm2 when irradiating VT1-0 titanium alloy samples and j ~ 1 J/cm2 when processing VT6 titanium alloy samples; pulse number is 1, 5, 10, and 50). The surface of samples was subjected to preliminary mechanical grinding and polishing before irradiation. It was shown that surface defects are formed on the surface of the alloys after irradiation, namely craters of different shapes and geometries with a diameter from fractions of a micron to 80–100 μm. At the same time, the grain structure in the subsurface layer becomes more homogeneous in terms of grain size and equiaxial properties. The initial state of titanium alloys is characterized by a fairly homogeneous structure with an average grain size of ~0,31 μm for VT1-0 and ~0,9 μm for VT6. After one irradiation pulse, grain growth to 0,54 μm in the transverse direction is observed in the subsurface layer of the VT1-0 alloy (j ~ 3 J/cm2), while grain size decreases to ~ 0,54 μm in the VT6 alloy (j ~ 1 J/cm2). After 50 pulses, the average grain size in the subsurface layer reaches ~2,2 μm for the VT1-0 alloy and ~1,6 μm for VT6. It should be noted that a rather uniform structure with equiaxed grains is formed as early as after treating with 1 high power ion beam pulse.

Aluminum/Copper Nanocomposites Fabricated by The Jet Vapor Depositiontm Process

1995 ◽  
Vol 382 ◽  
Author(s):  
Rebecca L. Lankey ◽  
L.M. Hsiung ◽  
H.N.G. Wadley ◽  
S.M. Karecki ◽  
D.T. Smith ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Alternative Model ◽  
Critical Thickness ◽  
The Novel ◽  
Total Thickness ◽  
Critical Layer Thickness ◽  
Jet Vapor Deposition ◽  
Transmission Electron ◽  
20 Nm

ABSTRACTAluminum and copper nanolaminates have been fabricated at Jet Process Corporation using the novel, proprietary Jet Vapor DepositionTM (JVD)TM process. Laminates with a total thickness of 10 μm were made by depositing alternating layers ofapproximately equal thicknesses of copper and aluminum onto preheated silicon wafers at asubstrate temperature of ∼140 °C. The layer thicknesses were systematicallyvaried between 20 nm and 1 μm. The microstructure and properties of the laminates were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nanoindentation methods. TEM has shown that the laminates have a strong {111} texture. The hardness results show that above a critical layer thickness of approximately 50 nm, the yield strength of the composites varies inversely with thelayer thickness, while the strength of nanolaminates with layer thicknesses smaller than the critical thickness is better explained by the Koehler model. An alternative model recently proposed by Embury and Hirth fits the data equally well.

scholarly journals Influence of Hard Turning on Microstructure Evolution in the Subsurface Layers of Inconel 718

2014 ◽  
Author(s):  
H. Touazine ◽  
M. Jahazi ◽  
P. Bocher
Keyword(s):  
Microstructural Evolution ◽  
Inconel 718 ◽  
Subsurface Layer ◽  
Cutting Speed ◽  
Advanced Characterization ◽  
Machining Parameters ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
Characterization Methods ◽  
Subsurface Layers

This study investigated the effects of semi finish, finish and critical finish machining parameters on the microstructural evolution of subsurface layers in Inconel 718. In order to assess the microstructural evolution in the subsurface layer following machining, advanced characterization methods including opto-digital microscopy, X-ray diffraction and nanoindentation were used. Results showed that friction between the tool and the workpiece during machining lead to microstructural changes such as hardness enhancement on the surface, and softening on the subsurface. It was also observed that damage in the machined surface is related to the presence of defects such as cracks, cavities and carbide detachment from the surface. Finally, residual stress measurements revealed that, within the investigated parameters, the cutting speed has the most significant effect on surface integrity.

scholarly journals Resolving 500 nm axial separation by multi-slice X-ray ptychography

2019 ◽  
Vol 75 (2) ◽  
pp. 336-341 ◽  
Author(s):  
Xiaojing Huang ◽  
Hanfei Yan ◽  
Yan He ◽  
Mingyuan Ge ◽  
Hande Öztürk ◽  
...  
Keyword(s):  
Imaging System ◽  
Axial Direction ◽  
Depth Of Field ◽  
Experimental Demonstration ◽  
Thick Sample ◽  
X Ray ◽  
Wavefront Propagation ◽  
Propagation Effects ◽  
20 Nm ◽  
Frequency Features

Multi-slice X-ray ptychography offers an approach to achieve images with a nanometre-scale resolution from samples with thicknesses larger than the depth of field of the imaging system by modeling a thick sample as a set of thin slices and accounting for the wavefront propagation effects within the specimen. Here, we present an experimental demonstration that resolves two layers of nanostructures separated by 500 nm along the axial direction, with sub-10 nm and sub-20 nm resolutions on two layers, respectively. Fluorescence maps are simultaneously measured in the multi-modality imaging scheme to assist in decoupling the mixture of low-spatial-frequency features across different slices. The enhanced axial sectioning capability using correlative signals obtained from multi-modality measurements demonstrates the great potential of the multi-slice ptychography method for investigating specimens with extended dimensions in 3D with high resolution.

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