Green's functions for body-centred cubic lattices

The presented paper contains the tables of Green's functions for bcc lattices for outband frequencies 1·0/ _m 1·6. The central-force model is used, the interaction with 8 nearest and 6 next-nearest neighbours is considered and the number of different Green's functions is fairly decreased by symmetry. Numerical difficulties arising by computing Green's functions are discussed. The derivation of symmetry relations for a dynamical matrix is generalized for the matrix of Green's functions.     

Space-charge limited currents in insulators with the Gaussian distribution of traps

A direct mathematical procedure is presented for obtaining the volt-ampere characteristic in an insulating material having Gaussian energy-distribution of traps, under the condition of space-charge-limited emission into the material. The current-voltage dependence is of the V ⁿ type; the exponent n depends on the temperature and the width of the Gaussian distribution. The current-voltage dependence derived for the Gaussian trap energy distribution is formally identical with the case of exponential distribution of the trap density in energy.     

Exciton system heating in ZnSe single crystals under laser excitation

The way to determine the effective temperature of the excitonic system from the study of the edge luminescence high energy region is motivated. Experimental data on the exciton heating in ZnSe single crystals under laser excitation are presented. The effective temperature of excitons T_x has reached 158 K at the lattice temperature T_L = 77 and the peak excitation intensity 2.7 MW cm^?2 (hv₀ = 3.50), while the excess temperature of the excitons (T_x ? T_L) increases as a square root of the pump intensity. Exciton-hot-electron, exciton-hot-photon, exciton-exciton interactions and excitonic Auger process are considered as possible causes of the exciton system heating.     

Hamiltonian circuits in Cayley graphs

The following result is proved: If either G is a finite abelian group or a semidirect product of a cyclic group of prime order by a finite abelian group of odd order, then every connected Cayley graph of G is hamiltonian.     

Theory of moving striations in plasma of D-C discharge I. Basic equation and its general solution

As a base for the theory of moving striations a partial integro-differential equation (26) is derived from the equations of continuity (1), (2), the Laplace-Poisson equation (3) and relation (4) between the electric field and the temperature of the electrons. Apart from the processes necessary for the actual formation of striations according to [1] and for the amplification of the wave of stratification according to [2], the equation also includes the processes defining the Debye length of the electrons, the influence of the axial electric field and of its local deflections on the motion of current carriers and the direct influence of the deviations in concentration of the electrons on the rate of production of current carriers. In deriving the equation the main attention is paid to the physical sense of the mathematical operations applied. The general solution is found by the method of the two-sided Laplace transformation and is described by triple integral convolution (42).

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I.

(1), (2), - (3) (4) (26). , , [1], , [2], , , . . (42).

     

Thermo-oxidation of polypropylene in the presence of triphenylphosphonium cyclopentadienylide

From measurements of weight losses of samples of isotactic polypropylene (IPP) with triphenylphosphonium cyclopentadienylide (TPCP) under various conditions and from the measurements of time courses of chemiluminescence, kinetic parameters of the process were determined. At concentrations of TPCP >1 wt%, the rate of loss of weight changes with the additive concentration. Compensation of the values of activation energy and pre-exponential term, determined from thermo-oxidation of IPP alone and IPP with TPCP, indicates that interaction of TPCP with oxidized polymer is complex.