Volume 39, Issue 2

The question is often asked how to interprete quantum physics. That question does not arise in classical physics, since Newton's axioms are immediately connected with basic ideas and experiences. The same is possible in quantum physics, if we remember how elementary particle physicists describe their experiments. As Helmholtz has pointed out. the basic assumption of classical physics is that of geneidentity. That means: Bodies remain the same during their motion. Obviously, that is no longer true in quantum physics. Particles can be created and annihilated. Therefore creation and annihilation must be considered as basic processes. Motion only occurs, if a particle is annihilated in a certain point, if an equal one is created in an infinitesimally neighbouring point, and if this process is continuously going on during a certain time. Motions of that kind are compatible with the existence of some manifest creation and annihilation processes. If we accept this idea, quantum physics can be derived from first principles. As in classical physics, we know therefore what happens from the very beginning. Thus questions of interpretation become dispensable. A particular mathematical method is used to exhaust continua. The theory is formulated in a finite lattice, whose point density and extension equally go to infinity. All calculations are therefore performed in a finite dimensional Hilbert space. The results are however related to an infinite dimensional one. Earlier calculations may, therefore, be essentially correct, though they must be rejected in theories which are based on manifestly infinite dimensional Hilbert spaces. Here limiting processes do not occur in the state space. They are only admissible for numerical results.

The processes leading to the population inversion are investigated in a recombining hydrogen plasma which is interacting with a cool and dense neutral hydrogen gas by using the rate equations on the basis of a collisional-radiative (CR) model and the energy equations for electrons, ions and neutral particles. The quasi-steady state (QSS) approximation is used only for the levels i lying above a certain level i* which is not the first excited level. The calculations have shown that the quasi-steady state cannot be realized while intense energy-flows due to the collisional processes exist between different kinds of the particles such as the electrons and the ions in the plasma, and that the population inversion is realized only in the quasi-steady state following the transient phase. The effects of the initial conditions of the hydrogen plasma and of the introduced neutral hydrogen gas on the overpopulation density are also discussed.

The Borel Summation Method is applied to obtain a first order formula for the bound states for the potential V(r) = F/r 2 + G/r + H/(r + z 2 ). For small H our formula reproduces the numerical results given by Znojil.

Measurements of both the 51 V and 195 Pt Knight shift in the V 3 Pt compound are reported for temperatures ranging from 300 K to about 1300 K. The temperature coefficients of the Knight shift and the NMR linewidth have been determined. An interpretation of the observations is given in the frame of a model which is based on the temperature dependence of the core polarization contribution to the total Knight shift.

Nuclear magnetic resonance studies of 123 Sb and 121 Sb in the Sb x Te 1-x liquid alloy system are described. Interest is focussed on the concentration dependence of the Knight shift and the NMR linewidth. Measurements of the Knight shift and linewidth have been carried out over the entire concentration range at elevated temperatures (900-1100) K. Knight shifts of 123 Sb and 121 Sb, measured to high precision, show hyperfine structure anomaly. Both. Knight shift and linewidth show strong dependence on the alloy concentration and extreme behavior at the concentrations 40 at.% Sb and 50 at.% Sb. respectively. The experimental results are discussed in terms of modes concerning the electronic structure of liquid semiconductors.

It is shown that the pairing property of Hückel molecular orbital energy levels holds also in the case of certain conjugated molecules containing heteroatoms.

The infrared spectra in the ν 1 /v 4 region near 1900 cm -1 of natural H 3 SnCl and monoisotopic H 3 116 Sn 35 Cl have been recorded with a resolution of 0.04 cm -1 . Isotopic and rotational fine structure has been resolved, and a rotational analysis based on 472 lines, σ(J, K) - 4.3x 10 -3 cm -1 , has been performed, ν 1 , and v 4 (v 0 = 1917.1932(7) and 1924.6790(4) cm -1 respectively in H 3 116 Sn 35 Cl) interact weakly by Coriolis x, y resonance, |ζ y l ,4| ~ 0.019. No further perturbations of ν 1 and v 4 were observed. The tin isotopic shift of v 4 is significant, Δν 4 relative to 116 Sn being -0.170(6) and -0.326(6) cm -1 respectively for 118 Sn and 120 Sn. The hot band (ν 3 + ν 4 ) - ν 3 has been observed, x 34 = + 0.423(5) cm -1 .

The ionic properties of the eutectic LiCl-KCl melt are examined in a large range of temperature and density. The radial distribution functions are calculated. It is shown that, although the contribution of the Coulomb energy to the thermodynamic properties decreases at high temperatures it remains always predominant and explains the temperature dependence of the specific heat at constant volume. The diffusion coefficients of Li + , K + and Cl - are determined. The mechanism of the ionic motion is studied through the memory function formalism. Two types of motion are detected, which arise from binary collisions and from dynamical events which involve a large number of ions. Temperature and volume changes show that the lithium ions remain always surrounded by a more structured atmosphere which hinders their motion. This effect becomes more apparent at high temperature and low density.

Results of ab initio SCF calculations on phospha-alkynes R-C≡P with R=H. CH 3 , NH 2 , OH. F and Cl are reported. The geometries were optimized by the force method with analytical gradient employing double zeta (DZ) basis sets. Various molecular and one-electron properties are calculated with double zeta plus polarization functions (DZ + P) and compared with experimental ones. The effect of substituents is analysed in terms of computed properties.

Ab initio configuration interaction (CI) calculations of the ground, electronically excited and the ionized states (cations) are reported for CuF 2 and CuCl 2 . The calculated results are compared with available experimental values of the UV spectrum of CuCl 2 and the ionization potentials obtained from the photoelectron spectrum of CuF 2 .

The results of molecular dynamics simulations of low and high pressure liquid water using a modified central force potential have been analyzed in order to study the effect of pressure on the hydrogen bond structure of water. The properties investigated and discussed include the hydrogen bond angle distribution, the O -O distance distribution between the neighbour molecules, the structure of the first coordination sphere in the high density liquid and the average number of hydrogen bonds.

The volume ratios of the mobile and stationary phases in thin layer chromatography, and the partition coefficients of halide and halate anions and some other anions between these phases were obtained by developing the ions simultaneously with a series of metaphosphates. The water contents of the developing solvents influenced the volume ratios very much, but not so much the partition coefficients. The logarithm of the partition coefficient of the halide anions is proportional to the reciprocal of their ionic radius, and that of the halate anions and oxoanions to the partial charge on the oxygens of them.

PrPS 4 crystallizes in the tetragonal system, space group I4 1 /acd with the lattice constants a= 1091.4(5) pm. c = 1936.1(8) pm. In the structure there are slightly distorted PS 3- 4 tetrahedra as discrete structural units, placed along the b-axis. Far infrared, infrared and Raman spectra of this compound have been recorded. The observed frequencies are assigned rangewise by factor group analysis and the Td-D 4h -correlation. The Raman data of rare-earth ortho thiophosphates LnPS 4 with Ln = La, Ce, Pr, Nd, Sm, Tb and Tm are given in a line diagram.

Studies on the electron transfer in the excited state from electron donors: acridine, 9- aminoacridine and its derivatives, including nitracrine and its isomers, to CCl 4 as a suitable electron acceptor, were undertaken. UV radiation (λ= 366 nm), absorbed only by acridine bases, generates CI - ions. The fluorescence quenching measurements indicate that no interaction appears between molecules of acridine bases in the excited singlet state and CCl 4 molecule. A scheme of photochemical processes is proposed which assumes that the triplet state of the base molecule is the reactive one.

The temperature dependence of the Knight shift of both 51 V and 71 Ga in the V 3 Ga compound has been measured over the entire range from 300 K to 1300 K. The results are discussed using a model based on the assumption that the core polarization contribution to the total Knight shift is the temperature dependent term.

Measurements of the 115 In Knight shift and the NMR linewidth in liquid In-Ni have been carried out over the concentration range (0-50) at.% Ni at high temperatures. With changes of the Ni concentration important changes occur in the hyperfine interactions referring to 115 In. The experimental results for higher Ni concentrations are in good agreement with a model involving a significant d-d exchange interaction.