The possibility of stable generation of intense characteristic Cs radiation upon electronic excitation of a Mo anode target heat treated in Cs and O2 vapors is demonstrated. The radiation source is a microfocus transmission type X-ray tube with a beryllium window and an S20 photocathode. A Cs-Mo-O layer is formed on the initial target in the form of a 1-µm-thick Mo film during heat treatment. The L and K spectral series are measured in an anode—cathode voltage range of 10—47 kV. A stable generation mode is observed at an electron flux power density up to 600 W/cm2. The energy of the Cs Kβ spectral line is in the region of photoabsorption peaks of the I and Xe atoms, which are widely used in the composition of contrast agents for medical diagnostics. This allows obtaining two- and three-dimensional images with the maximum contrast.

A point source of X-ray radiation with an energy range of up to 40 keV has been developed on the basis of a specially designed image converter tube. The source is capable of operating in pulsed and continuous modes. The main purpose of this is to use the source for testing X-ray streak cameras. The device can also be used in X-ray microscopy and spectroscopy as a reference radiation source, in biomedical research, and in other fields.

The possibility of the efficient band reject filtration of the continuous X-ray excitation spectrum in the energy range E ≥ 8 keV is demonstrated. This makes it possible to strongly increase the sensitivity of energy dispersive X-ray spectroscopy at detecting of weak fluorescence lines. Spectral rejection is implemented by transmitting a primary beam through highly oriented pyrolytic graphite with given structural parameters. Diffraction extinction in pyrolytic graphite ensures the possibility of reducing the intensity by more than 20 dB and rejecting the spectral band with a width of ~1 keV. The reduction of statistical fluctuations of the background of elastically scattered radiation is achieved when the bottom of the formed spectral valley is adjusted to the analyzed fluorescence line. The proposed scheme of band reject filtration also allows the suppression of intense characteristic lines in the primary and scattered radiation spectra.

The morphology of low-temperature (growth temperature 360 °C) multilayer Ge/Si heterostructures with Ge quantum dots was investigated by means of transmitting electron microscopy, scanning tunneling microscopy and X-ray optics. The possibility to determine integral morphological characteristics of heterostructures’ layers using X-ray optics method is shown. The results of X-ray optics are in a good agreement with TEM measurements and we discover the cross-correlation between Ge layers in heterostructures containing thin Si spacers. The spectral sensitive region of structures under investigation is estimated by measuring photo-emf spectra at the temperature of 78 K and 300 K. The possibility of controlled forming of spectral sensitive region of Ge/Si heterostructures in the range of 1.5 – 2.8 μm is verified.

Normal 0 false false false RU X-NONE X-NONE The combination of methods of voltammetry, Raman spectroscopy, and X-ray reflectometry for the first time has been applied for the more comprehensive investigation of interfacial boundaries of GaAs, i.e. determination of phase distribution and thickness of the phase layers. The conditions for the formation of elemental arsenic on a GaAs surface in the process of selective dissolution are discussed. The stability of interfacial boundaries in air has also been studied. The investigations have shown that air storage lead to the oxidation of formed As0 and reorganization of GaAs interfacial boundary accompanied by the formation of Ga2O3 and As0 as a result of a reaction between As2O3 and GaAs. The results on interfacial boundaries composition were found to be correlated with the theoretical data. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Обычная таблица"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

The dispersion characteristics of film X-ray monochromators made of pyrolytic graphite (PG) are investigated. The analyzed samples are made of two PG types: HAPG structurally perfect pyrolytic graphite developed for high-resolution X-ray spectroscopy and HOPG pyrolytic graphite used in standard PG monochromators. The schemes for measuring emission spectra and the fine structure of absorption spectra by single X-ray shots are considered. The conditions for recording spectra in a ∼1-keV-wide band including the XAFS and NEXAFS regions are substantiated. The feasibility of independent measurements in a few X-ray spectrum bands is demonstrated. The design of the dispersive element based on a diamond-pyrographitediamond structure for spectrum measurements at superhigh radiation exposures is proposed.

Features of X-ray refraction (XR) in thin, weakly absorbing films of beryllium and carbon are considered for radiation with a wavelength of λ ∼ 0.1 nm incident at a small grazing angle. It is established that an interference modulation of the angular diagram of XR appears due to the elastic wave scattering on defects of the film surface and the subsequent specular reflection from the film-substrate interface. The proposed experimental scheme of XR observation and the corresponding calculation model ensure determination of the film thickness at the sample edge to within ∼1%.

A new experimental scheme for the measurement of the x-ray reflectivity R from a liquid-solid interface in the range of angles of total external reflection is proposed. An x-ray beam is transmitted through a plane channel filled with a liquid under investigation. The channel is formed by two optically polished plates, one of which being the substrate under study. To eliminate the edge effects caused by surface tension, polymer films with a lyophilic coating are used as windows of the channel. For wate-silicon and glycerol-silicon interfaces, the angular dependences of R and the parameters of the interfaces are measured with the scheme developed using the Cu K α (8.05 keV) and Cu K β (8.91 keV) lines.

The relative x-ray reflectometry (RXR) technique has been used for the first time for determining the parameters of a discrete layered structure. The scheme of x-ray optics used for these measurements on two wavelengths is described, the conditions of applicability of the proposed method are formulated, and the algorithm of data processing is described and justified. The results of RXR measurements for a test structure prepared by magnetron sputtering of tantalum onto a silicon substrate via a mask with periodically arranged windows are presented. The proposed RXR scheme can be used in semiconductor technology for the monitoring of parameters of device structures containing nanolayers.

The radiography with micro focus x-ray tube is very promising for use in non-destructive industrial control, medical and biological x-ray imaging. We investigated a micro focus x-ray tube with hollow anode to find the smallest available focal spot sizes under the different values of the X-ray tube load. The electron beam focusing system of the x-ray tube was designed with the use of the deflection-coil assemblies and a short focusing lens. Under varying the tube power load from 20W to 70W we found that the X-ray focal spot size (fall width at half maximum-FWHM) is changed from 25 mu m to 54 mu m. The methods of focal spot size measurements are shortly described. Examples of radiographic images of the pair-line object target (phantom CIRS 11A) are presented. The phantom study showed the resolving power 18 pl/mm divided by 20 pl/mm. Practical applications of the developed X-ray apparatus are discussed in the report.

The X-ray projection microscope with the use of polycapillary optics is described. The focusing Kumakhov lens with a focus size of 1 50 m and an energy-dispersive Si-detector allow local analysis of chemical elements concentrations and distributuions. The same lens can be used for local radiation procession with a dose rate up to 10 Gy/s. Digital projections are recorded by the 1300x1030 detecting array with a pixel size of 6.7 μm. The radiation spectrum can be strongly modulated by changing X-ray source voltage, rotation the filter cassette, and by placing in the incident beam the polycapillary half-lens. Conditions for enhancing image contrast by the digital subtraction of X-ray projections registered at different spectrum distributions in the energy range of 5-25 keV are considered. It is shown that when an object is irradiated by polychromatic radiation, the use of a Ni filter and a NiCl2 contrast solution provides results that were previously obtained by subtracting images with monochromatic spectral lines near the K-jump of absorption in the contrast media. X-ray fluorescence spectra and contrast enhanced images of biological objects are presented.

Investigation of ion-implanted structures by means of X-ray reflectometry was carried out. For this purpose the new methods of reflectivity measurements and the experimental data treatment were developed: double beam method of X-ray reflectometry and the subtraction of trend. The depths or widths of implanted layers, its average density were determined.

Tunneling of 0.154-and 0.139-nm x-ray photons through a thin film under total internal reflection conditions has been experimentally demonstrated. The NiSi2 film 13 nm thick is deposited by magnetron sputtering on a polished Si substrate. A beam with an angular spread of 20″ is directed to the Si/NiSi2 interface from the inside through the lateral surface of a sample. A peak associated with tunneling of photons from Si to air through the NiSi2 film is observed at grazing angles of θ1 > 0.4θc, where θc is the critical angle of total internal reflection at the Si/NiSi2 interface. The integral intensity of tunneling peaks that is measured for various θ1 angles agrees with the calculations.

X-ray absorption spectra of a number of samples were measured in the range 5–30 keV by the prism spectrophotometry method. The spectral decomposition was performed using an optically polished diamond prism with an opening angle of 90°. The absorption spectra of liquid bromonaphthalene are presented as an example. An energy resolution of 100–130 eV was achieved in the energy range of ∼10 keV, providing the unambiguous identification of elements by jumps in the K photoabsorption.

Conditions for enhancing image contrast by the digital subtraction of X-ray projections registered at different spectrum distributions in the energy range of 5–25 keV are considered. An experimental scheme for recording digital projections based on a 1300 × 1030 detecting array with a pixel size of 6.7 μm is described. It is shown that, when an object is irradiated by polychromatic radiation, the use of a Ni filter and a NiCl 2 contrast solution provides results that were previously obtained by subtracting images on monochromatic spectral lines near the K jump in the absorption of the contrast substance. Schemes for recording color X-ray images in a dynamic mode using semitransparent X-ray monochromators are proposed.

A method for determining the parameters of multilayer nanostructures by measuring the angular dependence of the X-ray reflectance at two wavelengths has been considered. A calculation scheme taking into account the specificity of the method was suggested, which allows operation with samples of any size and shape. The scheme was applied to C/Ni/C, Si 1− x Ge x , and Al x Ga 1− x As multilayer structures. It was shown that two-wave reflectometry allows elimination of the influence of instrumental errors; hence, the thickness, density, and composition of both polycrystalline and monocrystalline nanostructure layers reliably determined.

New X-ray optical methods—two-wave reflecto- and refractometry—have been used for the first time for the determination of GexSi1−x/Si composition and exact measurements of multilayer heterostructure thicknesses. Both techniques are based on simultaneous measurements of two intense characteristic X-ray lines separated from the polychromatic X-ray probe by semitransparent monochromators. X-ray reflectometry of multilayer structures completely eliminates intensity drift influence and geometrical errors at small grazing angles. The refractometry technique provides direct determination of refractive index decrement and the respective value of x in a solid solution with ∼1% accuracy. Refractometry data are not influenced by mechanical strain and by presence of overlaying thin film structure.