Excess and partial excess molar volumes of mixing of N,N-dibutyl-2-ethylhexamide with dodecanol

Excess and excess partial molar volumes of mixing of the system N,N-dibutyl-2-ethylhexylamide (DBEHA) + dodecanol (DDA) were determined at 25, 35, 45, 55 and 65°C. The excess molar volumes exhibit a maxima at each temperature at approximatelyx _DBEHA = 0.3 and a minima close tox _DBEHA = 0.9. The values of the excess volumes in general increase with the temperature. The partial excess molar volumes are calculated from the smoothed data and the results are discussed in the light of postulated amide-alcohol interactions.     

Determination of heptacaine hydrochloride in solution using nuclear analytical methods

The applicability of two nuclear analytical methods for the determination of hepatacaine hydrochloride in solution was studied, i. e. radionuclide X-ray fluorescence analysis and radiometric titrations based on precipitate formations. Methods used were evaluated on the basis of obtained sensitivity values.     

Production of lepton pairs in processes with hadronic jets

We propose a model for the production of extra (additional) lepton pairs in deep inelastic lepton-hadron scattering, e⁺e^– annihilation and large p_T processes. Extra lepton pairs are supposed to be originated by annihilations of quarks and antiquarks created during the space-time evolution of quark initiated jets. This mechanism yields predominantly dileptons with rather low masses. Predictions following from the model are compared with the recent data on trimuon production in neutrino-nucleon interactions. It is also suggested that internal hard processes can lead to dileptons with both small and large masses. The latter mechanism has rather small cross section but it is particularly interesting from the point of view of the simple quark-parton model.Dedicated to Academician Václav Votruba on the occasion of his seventieth birthday.     

The relation between deep trapping levels and the structure of Se layers

Using electron microscopy methods it has been determined that there are numerous crystalline inclusions in evaporated layers of amorphous selenium. The density, dimensions, modification and distribution in the cross section of a layer are essentially dependent upon the method of layer preparation. The maximum micro-inclusion density is observed in layers evaporated at a substrate temperature (t_s) between 8 to 30°C. These layers also possess crystallites of monoclinic modification. In layers evaporated at t_s ? 50°C inclusions of trigonal modification prevail.The parameters of the deep trapping levels for holes and electrons have been determined from photodischarge kinetics. The origin of these levels is found to be related to the phase transition. The hole traps are caused by the crystalline formation of trigonal modification, and the electron traps by crystallites of monoclinic modification.     

Birefringence in YAlO3∶Ce between 2–5 eV

This contribution presents birefringence spectra for orthorhombic YAlO₃Ce single crystal in the region 2–5 eV. The spectra were measured by means of a reflection method of null ellipsometry and were compared with spectra of YAlO₃:Nd determined from values measured in the region of lower energies (1·1–2·2 eV). We have found that there are differences between the spectra of YAlO₃Nd and YAlO₃:Ce which are most pronounced in thea-axis direction.The author is most grateful to Ing. . Viovský CSc. for helpful discussions during the course of this work and to Monokrystaly Turnov for preparation of the samples.     

Some remarks on the two-body-problem in geometrodynamics

The interest in the two body problem in geometrodynamics and its present status are discussed. Special consideration is given to time-symmetric initial data. An equation relating the “bare mass energy,” the potential energy and the “vibrational energy” at the initial moment is proposed. The significance of coordinate conditions in dynamical equations is discussed next. Conditions implying maximal slicings of spacetime and harmonic coordinates in those slices are considered in detail, as they seem to be well suited for numerical calculations and for interpretation of the results of such calculations.     

Deposition of copper films by unbalanced d.c. magnetron sputtering

The electrical resistivity of as deposited polycrystalline copper thin films as a function of varying the process parameters has been investigated. Trying to minimize the resistivity of the copper thin films is important in the semiconductor industry, due to the fact that low resistivity copper can be employed to great advantage for new metallization schemes in advanced ultralarge scale integrated circuits. This paper presents the optimum choice of parameters that are necessary to achieve low resistivities of the thin films in reproducible experiments. All the depositions were performed using an unbalanced d.c. planar magnetron sputtering source (consisting of a circular copper target (98% purity, 0.01% Fe, 0.005% Ni, 0.005% Si) with a diameter of 100mm fitted with two electromagnets). The copper thin films were deposited onto glass substrates with argon being used as the sputtering gas. The resistivity was studied as a function of the pressure of the sputtering gas, the substrate bias, the substrate to target distance, the magnetron power, and the substrate temperature. It was found that depositions producing thin films with a resistivity of that approaching the bulk material (1.7×10^–8m) were obtained if the sputtering gas pressure was below 0.2 Pa. The effect of the substrate bias was insignificant at these pressures. The crystallographic structure of the copper thin films, determined by X-ray diffraction, is also reported.The authors would like to thank Dr. Soukup for his support during this research. We would also like to express our gratitude to Mr. A. Rajský for improving the design of the sputtering device. This work was partially financed by a grant from the Grant Agency of the Czech Republic No. 202/93/0508.     

Modal resonant ultrasound spectroscopy for ferroelastics

Recent experimental and theoretical improvements of resonant ultrasound spectroscopy (RUS) are summarized to investigate elastic constants of phases in shape memory alloys. The proposed inversion procedure, described in this work, is particularly suitable to reliable evaluation of the temperature dependence of elastic constants of low-symmetry ferroelastic materials which may be strongly elastically anisotropic and tend to exist in twinned forms. The method is applicable even for the evaluation of single-crystal elastic constants from RUS measurements on microtwinned crystals, since it involves a homogenization algorithm based on the macroscopic deformation response of the layered structure. This potentially allows performing meaningful acoustic studies on samples with a general submicron-size layered structure.     

Analytic solution for the nondegenerate quantum control problem

We present an analytic solution for the nondegenerate quantum control problem, i.e., the transfer of a deliberate amount of population, 0%-100%, between arbitrary initial Psi(t)> and final Psi'(t)> states, which can be expanded in terms of nondegenerate energy eigenstates k>. The solution constitutes a robust two-photon multicomponent adiabatic passage, via an intermediate eigenstate 0>, which relies on three types of "null states."