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111.
V. Čápek 《Czechoslovak Journal of Physics》1978,28(9):995-1002
The thermoelectric power in the Anderson model of electrons in localized states in the mobility gap of semiconducting glasses interacting by attractive forces is calculated at low temperatures. Under some conditions, a transition from the activated form ofS to S=const at low temperatures is predicted. In connection with the activated character of the conductivity, it well corresponds to the experiment on some chalcogenide glasses.The author would like to thank ing. V.Cháb for communicating him the experimental data on As2Te3TIx prior to publication. 相似文献
112.
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115.
Formation of the plasma potential in a plasma that contains energetic electrons and is bounded by a floating collector that
emits electrons is studied theoretically. The problem is treated by a static. kinetic plasma-sheath model of Schwager and
Birdsall [Phys. Fluids B2 (1990) 1057], which we have extended in order to include additional energetic electron population. The distribution of these
electrons is assumed to be a high-temperature Maxwellian. They are called hot electrons. In the paper we study effects of
the density and temperature of the hot electrons on the formation of the plasma potential. The model shows that for certain
densities and temperatures of the hot electron population plasmas with two different plasma potentials can coexist in the
system. These two plasmas are separated spatially by a double layer. For the case when there is no emission of electrons from
the collector, results of the model are compared with computer simulation and very good agreement between the model and the
simulation is found. The simulation also confirms existence of two plasmas with two different potentials separated by a double
layer. 相似文献
116.
The presence of dust grains is a common phenomenon in the space environment. Grains can be charged by many different processes (e.g., photoemission, attachment of electrons/ions, the secondary emission, etc.). If the grain's surface potential becomes high enough, one can observe field emission of ions or electrons. We are trapping a single dust grain in a Paul trap, expose it to a low-energy electron beam, and investigate the evolution of its charge-to-mass ratio with respect to the energy of primary electron beam. We use micron-sized (D = 2–11 m) glass grains and charge them up to -300 V of surface potentials; it corresponds to the electric field strength of about 108 V/m. Analysis of the charging/discharging processes has shown that (1) the effect of the field enhanced secondary emission is negligible in the case of insulators and (2) the effective work function for electron field emission from charged insulators is as low as 1 eV. 相似文献
117.
Considering the Markov binomial distribution, we study large deviations for the Poisson approximation. Apart from the standard choice of parameters, we use the approach where the parameter of approximation depends on the argument of the approximated distribution function. 相似文献
118.
Zvonko Čerin 《Geometriae Dedicata》2001,84(1-3):41-47
This paper improves an old theorem about a rectangular hyperbola
: its centre lies on the pedal circle of any point on
with respect to any triangle inscribed in
. We also prove that an analogous result holds for Cevian circles. These results are used to obtain new characterisations of the Feuerbach, Jarabek, and Kiepert hyperbolas of a triangle. 相似文献
119.
120.
It is well known that in the non-depleted pump approximation, the efficiency of a second harmonic generation (SHG) of a guided mode in a non-linear optical waveguide increases quadratically with the interaction length (P
2 L
2), and linearly (P
2 L) in the erenkov regime. The efficiency of the erenkov SHG in the waveguide with a non-linear substrate and linear guiding layer is known to be strongly peaked at a particular pump wavelength and a particular waveguide thickness, with the erenkov angle approaching zero. The known theory predicts an infinite efficiency value at the peak, however. In this contribution, a simple integral expression for the SHG efficiency in the erenkov regime is derived. For large erenkov angles and interaction lengths it yields the expected P
2 L dependence, while in the limit of small erenkov angles the dependence is found to have the form of P L
3/2, possessing also a finite value at the efficiency peak. The condition determining the accurate position of the efficiency peak in the waveguide thickness–pump wavelength plane is given, too. 相似文献