Evaporative Cooling and Self‐Thermalization in an Open System of Interacting Fermions

Depletion dynamics of an open system of weakly interacting fermions with two‐body random interactions is studied. In this model, fermions are escaping from the high‐energy one‐particle orbitals, that mimics the evaporation process used in laboratory experiments with neutral atoms to cool them to ultra‐low temperatures. It is shown that due to self‐thermalization the system instantaneously adjusts to the new temperature which decreases with the course of time.     

Valence state of manganese ions in the La1−α BiLaβMnLa1−δ OLa3±γ ceramics

The valence state of the Mn ions in ceramic samples of the La_1?α BiLa_βMnLa_1?δ OLa_3±γ composition (LBMO) has been studied using the X-ray photoelectron spectroscopy. The presence of Mn³⁺ and Mn⁴⁺ ions in these compounds has been shown. The relative content Mn³⁺/Mn⁴⁺ has been determined by means of fitting the experimental Mn 2p spectra by the superposition of theoretical spectra of Mn³⁺ and Mn⁴⁺ ions. The elemental composition of the samples has been determined by the X-ray photoelectron spectroscopy and electron probe microanalysis. It has been established that the relative content of Mn⁴⁺ ions correlates with parameter δ, which characterizes the deviation of the actual elemental composition of the La_1?α BiLa_βMnLa_1?δ OLa_3±γ ceramics from stoichiometry La_{1 ? x} Bi _x MnO₃.     

The effect of injected-charge spatial distribution on the x-ray induced electron emission intensity in ferroelectric electrets

The nonmonotonic behavior of electron emission intensity induced in a surface layer of a ferroelectric electret by soft x-ray irradiation with an injected charge depth is predicted using a model of an accelerating electric field. The predicted behavior is in agreement with the results of the model experiments.     

Computer simulation of integral and differential optical characteristics of paints

A method of calculating the integral and differential characteristics of paints is proposed. The method is based on statistical simulation (the Monte Carlo method). For white alkyd enamel formed on the basis of titanium dioxide, the results of calculations of the reflectance, absorptance, covering power, and distribution of the absorbed energy over the layer as a whole, along with the absorptance of the pigment and the binder separately, are presented.     

Spectra of low-energy electrons excited by soft x rays

A study is made of the x-ray photoemission spectra of low-energy electrons (E _kin=0–30 eV) and its dependence on the way in which the potentials are applied to the entrance system of the analyzer. It is shown that under certain experimental conditions the spectrum consists solely of electrons emitted from the sample. The x-ray photoemission spectrum of pure silver is found to have a fine structure, which disappears when a surface layer of carbon or oxygen is deposited on the surface. The spectrum then takes on the “cascade” form. A possible interpretation of the fine structure is suggested in the framework of band theory. Zh. Tekh. Fiz. 67, 73–77 (March 1997)     

The relaxation dynamics, iron valence state, and M?ssbauer effect in PFN ceramics

The dielectric properties, X-ray emission spectra, and M?ssbauer effect in ceramics made of PbFe_1/2Nb₁/₂O₃ (PFN) compound were studied. The relaxation dynamics revealed above Curie temperature TC at a frequency of 3 × 10⁻²–10⁵ Hz is described in detail. Analysis of the X-ray emission and M?ssbauer spectra showed that at room temperature (T = 300 K), the iron ions in PFN are mainly in the high-spin valence state Fe³⁺. The M?ssbauer spectral parameters obtained at T = (300, 353, and 393 K) indicate an octahedral environment for Fe³⁺ in both the ferroelectric and paraelectric phases.     

Surface compositions of 9XC and R6M5 tool steels after laser pulse irradiation according to X-ray photoelectron spectroscopy data

The composition of a multicomponent oxide layer formed by laser pulse heating in air is investigated via X-ray photoelectron spectroscopy. Investigations are performed by means of a SPECS surface analysis system using AlK _{α1, 2}-line radiation. The structures of oxide-metal interfaces within the surfaces of 9XC and R6M5 multicomponent steels have been examined.