Structure and optical properties (at (lambda) equals 0.154 nm and (lambda) equals 3.16 nm) of W - Ti, W - TiN, W - Sc and Cr - Sc multilayer x-ray mirrors for the long wave part of 'water window' wavelength range were studied by methods of the x-ray diffractometry and cross-sectional electron microscopy. The reflectivities at (lambda) equals 0.154 nm are increased going from W - TiN, Cr - Sc, W - Ti to W - Sc multilayers. Cr - Sc mirrors have highest reflectivity and resolution at (lambda) equals 3.16 nm. Influence of the ambient atmosphere on optical properties of multilayer mirrors is shown.

Space test of x-ray multilayer mirrors on the surface of Russian orbital station 'Mir' revealed that after a 5-month space exposure, multilayers consisting of chemically interacting materials (Mo - Si and WSi₂ - Si) preserved their periods. Preannealing at 570 K for one hour was sufficient to stabilize reflectivity at 1.54 angstroms of mirror WSi₂ - Si with period 33.6 angstroms. Preannealing at 770 K for one hour was not enough to stabilize reflectivity at 1.54 angstroms of MoSi₂ - Si mirror with period 77.7 angstroms (after space exposure its reflectivity was increased by 18% as a result of interface smoothing influenced by space effect agents).

The effect of elevated temperatures on the structural stability of Mo - Si and MoSi₂ - Si X-ray multilayer mirrors was studied. Multilayers deposited by magnetron sputtering were annealed at temperatures ranging from 300 to 1300 K. A detailed picture of the thermally induced changes in the microstructure is obtained using several techniques including small- and large-angle X-ray scattering and transmission electron microscopy. The main causes of the degradation of Mo - Si mirrors is an interdiffusion mixing of silicon and molybdenum layers and a formation of MoSi₂ in both the hexagonal and tetragonal phases. The smoothening of interfaces in MoSi₂ - Si mirrors and increasing of their reflectance were observed after annealing at temperatures T < 800 K. The MoSi₂ - Si mirrors undergo a catastrophic degradation at T > 1000 K caused by a crystallization of amorphous Si and a recrystallization of hexagonal MoSi₂.

Structural, phase and chemical stabilities of X-ray multilayer mirrors Mo-(B + C) with period in range 8 - 11.5 nm were studied at temperatures 250 to 1100 degree(s)C by small-angle and large-angle X-ray diffraction and electron microscopy methods. Two amorphizations at approximately equals 450 degree(s)C and approximately equals 750 degree(s)C and two crystallizations at approximately equals 650 degree(s)C and approximately equals 850 degree(s)C of Mo-based layers were observed due to formation of molybdenum carbides MoC (hex), (gamma) - MoC and Mo₂C instead of metal Mo and formation of molybdenum borides MoB₂ and Mo₂B₅ instead of molybdenum carbides, respectively. Both amorphizations of Mo-based layers were accompanied by smoothening of interfaces and by increase of multilayer X-ray reflectivity at (lambda) equals 0.154 nm. Both crystallizations of Mo-based layers promoted development of interface roughness and decrease of multilayers X-ray reflectivity. The destruction of Mo-(B + C) multilayers at approximately equals 1100 degree(s)C was caused by Mo₂B₅ layers recrystallization.

Annealing effects in short-period multilayers Cr₃C₂/C, TiC/C, Cr₃C₂/(B+C) and CrB₂/C were studied in wide temperature range approximately equals 200-1200 degree(s)C by X-ray scattering and cross-sectional microscopy. It was shown that thermodynamic equilibrium of layers materials at their interfaces and stabilization of layer structure by impurities and heat treatment are effective approaches to short-period multilayers with enhanced thermal stability of their structure and optical properties.

The effect of phase equilibrium at multilayer interfaces on melting temperature of multilayer x-ray mirrors is reported. Based on phase equilibrium diagram of alloys, approach to an estimation of melting temperature and component concentrations of metastable eutectics is suggested. Application of this approach to metastable Mo-Si and W-Si multilayer x-ray mirrors revealed that phase nonequilibrium can decrease substantially the multilayer melting temperature (by approximately equals 200 degree(s)C in case of metastable Mo-Si eutectic in comparison with the most light-melted stable MoSi₂-Si eutectic in the whole Mo-Si system).

Optical constants of Si, C, Mo, and Nb thin films as well as of fused quartz and float glass substrates have been determined experimentally in the (lambda) approximately equals 80 - 190 angstrom wavelength range. The dependence of optical constants on film thickness and film production technology is demonstrated. The factors influencing substance permittivity in the soft x-ray range are discussed. It is discovered that the main of them is the presence of impurities introduced into the film during its deposition. The chemical composition of multilayer Mo-Si x-ray mirrors is studied. It is shown that if O, N, and Ar impurities in Si films are taken into account, the available experimental data on the reflectivity and resolution of Mo-Si mirrors in the soft x-ray range can be described quantitatively.

The angular dependencies of the reflection coefficients of ultrasoft X- ray radiation by X-ray interference mirrors were investigated for samples prepared by two methods: magnetron spattering and electron beam evaporation. The theoretical evaluations of these reflection coefficients were compared with the obtained experimental results. The investigated multilayer X-ray mirrors were found to have extremely high quality.

The problem of multilayer mirrors which are capable to reflect X-ray radiation at two given wavelengths is discussed. Three kinds of two- period multilayers are considered and comparison of their properties in the soft X-ray region is presented. The scheme of soft X-ray scanning microscope on the basis of Schwarzschild objective with two-period multilayer coating is proposed for chemical microanalysis of biological samples.

Basic properties of whispering gallery mirrors in soft X-ray region are considered. The following applications of whispering gallery optics are discussed: increasing of utilization efficiency of point source radiation, deflection of synchrotron radiation beam to vertical plane and its transportation to another horizontal level, resonators for soft X-ray lasers and the use of whispering gallery effect for investigation of roughness of concave surfaces.

Applications of the whispering gallery (WhG) optics for the steering of the synchrotron radiation (SR) are considered. The general principles of operation of the vertical SR beamline for proximity X-ray lithography are discussed. The possibilities of the WhG optics for the transportation of the SR beam to the second floor and for the steering of the hard X-ray radiation are analyzed.

The X-ray reflection spectra of oxidized rare-earth metals are measured in the region of 4d-ionization threshold. The main features of the mentioned spectra are deep and wide minima in spectral dependencies of reflection coefficients near the 4d-edge of ionization. Experimental reflection spectra of rare-earth metals are compared with the 4d- absorption spectra of the same elements and also with the calculated values of reflection coefficients obtained by means of the atomic scattering functions.

Ultrasoft x-ray reflectometry methods was used to estimate an effect of surface technological treatments (mechanical and chemical polishing, laser annealing) on the atomic short-range order coordination of silicon atoms in the near surface region of SiO₂-based glass. Reflection spectra fine structure in the vicinity of SiL_2,3 ionization threshold for the different angles of incidence and the scattering indicatricies were measured. Analysis of the experimental data shows that polishing (both mechanical and chemical) leads to an appearance of the thin surface layer (thickness about 17 nm) characterized by (alpha) - quartz-like SiO₄ tetrahedron distortions. A degree of distortion depends on treatment and is the largest after chemical polishing and the lowest (but noticeable) after laser annealing. Angular shift of the anomalous scattering peak position is interpreted as a result of the average surface layer mass density decreases after laser annealing.

The roles of the absorption magnitude, the surface roughness with small correlation radii and the transition layer in the anomalous scattering peak formation have been considered. Joint measurements of scattering indictrices and near threshold specular reflection spectra fine structure have permitted to estimate a strong sensitivity of the anomalous peak to the presence of transition layers characterized by distortion of long-range order connected with some kind of macrodefects (like grain boundaries, disclinations, dislocations, etc.). Studying the layer system Si-SiO₂ a strong dependence of the intensity of this peak on the dioxide thickness has been discovered.

The possibilities of X-ray scattering methods are demonstrated for the quantitative study of supersmooth surface microgeometry. It is shown that the model of a surface which takes into account layered inhomogeneities near a surface enables one to obtain better agreement between theory and experiment in comparison with the step-like model of a surface which widely used elsewhere.

The influence of smooth (not step-like) variation of the dielectric function near a surface on reflectivity and scattering of X-rays is investigated theoretically. It is shown than the presence of the transition layer can essentially change the shape of differential scattering intensity diagram, especially when the incidence angle of X- ray beam is more than critical angle of the total external reflection. The application of model involved allows one to describe the Yoneda effect quantitatively (whereas it is impossible in the frames of a step- like model of the dielectric function).

The expression for X-ray scattering diagram by thin film roughness is obtained and analyzed in the perturbation theory approximation. Specific features of X-ray scattering are discussed which have no analogs in X- ray scattering from a single surface and are caused by the interference effects. These are: oscillations of X-ray scattering diagram, the lack of X-ray scattering from external film surface, and interference suppression (up to some orders) of X-ray scattering intensity.

Methods of X-ray optics, X-ray structure and fluorescence analysis were applied for superthin (3-100 angstrom) films investigation. The way of surface relief statistic characteristics determination by comparison of model calculations with experimental X-ray reflection curves is proposed. Surface Fourier-spectra were reconstructed by scattering indicatrices. The original method of X-ray analysis in grazing beam has been applied to films as thin as 15 angstrom. The results of investigation of film phase composition, density and microroughness in the stage of island growth and continuous layer formation in deposited metals Ni, Ti, Nb are discussed from the point of view of their different abilities for oxidation. The trend to strict constancy of nuclei height beginning with four monatomic layers has been found. Niobium films consisting of two- and three-layers of oxides and niobium solid solution (Nb-O) may be continuous already at 20 angstrom thickness. In titanium films at 15 angstrom thickness the transition from island state to continuous bilayer Ti/TiO₂ have been revealed.