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971.
F. Schümann S. Zavatarelli L. Gialanella U. Greife M. Junker D. Rogalla C. Rolfs F. Strieder H.P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):337-342
Abstact: The elastic scattering cross sections, σ (E,θ), for the systems He+Ta and He+W have been measured at θlab=165° and E
lab=76.1 keV to 3.988 MeV using targets with a thickness of a few atomic layers. The results are smaller than the results given
by the Rutherford scattering law, σR(E,θ), due to the effects of electron screening and can be described by σ(E,θ)/σR(E,θ)=(1+Ue/E)−1, where U
e is an atomic screening potential energy. The deduced average value, U
e=28 ± 3 keV, is consistent with the Moliére- and Lenz-Jensen-models as well as electron binding energies.
Received: 25 May 1998 相似文献
972.
O. Ya. Butkovskii Yu. A. Kravtsov E. D. Surovyatkina 《Journal of Experimental and Theoretical Physics》1998,86(1):206-212
The structure of the attraction zones of the final states associated with dynamical period doubling bifurcations is investigated.
It is found that on the “initial value—transition rate” plane the attraction zones of the two possible final states alternate
with each other and that a subdivision of the attraction regions occurs with a decrease in the transition rate. It is shown
that the boundaries of the attraction zones are smeared out because of the effect of noise and in this situation the fine
structure of the attraction zones is destroyed. As analytical and numerical calculations have shown, the critical value of
the noise variance, corresponding to the boundary between the dynamical (or predictable) and stochastic (or unpredictable)
modes, has a power-law dependence on the transition rate with a typical exponent value of one. The existence of “noise” invariants
is also observed: the integrated (over all initial values) probability of achieving the final state is invariant with respect
to the noise level.
Zh. éksp. Teor. Fiz. 113, 369–380 (January 1998) 相似文献
973.
974.
D. F. Kurdgelaidze 《Russian Physics Journal》1998,41(10):1042-1050
On the basis of nonassociative spinor field theory, the specific properties of a nonassociative spinor field are investigated.
A new quantum number is introduced: the associator, which is a measure of the nonassociativeness of the field. To calculate
the associator and spin in nonassociative algebra, open and closed products are introduced. It is shown that the spin consists
of two components: the first half (calculated by the open-product rule) is similar to ordinary spin, while the second half
(calculated by the closed-product rule) is attributed to the associator, i.e., is related to shear in the auxiliary isotopic
space. The associator basis is expanded to a complete octonion basis, and the Poincaré group of four-dimensional space is
expanded to a Poincaré group of eight-dimensional space. It is shown that, from these generators, in the particle rest system,
the nonzero independent eigenvalues are: one, the sign of the particle energy, one of the spin components, one of the associator
spatial components, and c7.
Tbilisi Medical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 101–109, October, 1998. 相似文献
975.
976.
E. D. Éidel’man 《Technical Physics》1998,43(11):1275-1279
A theory is developed for a new type of transition — a change in the ratio of the longitudinal and transverse dimensions of
a convection cell as the thickness of a liquid layer is varied. A sudden change in the ratio of the cell dimensions takes
place because of a change in the predominant mechanism for excitation of convection. The governing influence of buoyancy forces
gives way to one of thermocapillary forces, and they in turn give way to the influence of thermoelectric forces for yet thinner
layers. As the layer thickness is reduced gradually at a fixed external heating, the ratio of the dimensions will take on
the values 0.7, 0.65, and 1, respectively.
Zh. Tekh. Fiz. 68, 7–11 (November 1998) 相似文献
977.
An analytic expression is derived for calculating the intensities of individual spin-rovibronic lines in the fully resolved
gas phase electronic spectrum of a polyatomic molecule, in which one of the zero-order electronic states is a triplet state.
The expression is employed to calculate the effect of fine structure splitting on the singlet-triplet absorption spectrum
of pyrazine using the parameters available from experiment. A transition from Hund’s coupling Case (a) to Case (b) on going
from low J to high J rotational levels is predicted to occur at a moderate resolution of a few hundred MHz. The effect is more pronounced in pyrazine-d
4 and the pyrazine-argon van der Waals complex owing to their larger mass.
Zh. éksp. Teor. Fiz. 114, 63–90 (July 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
978.
The problem of calculating the noise factor of a traveling-wave gyrotron is solved for a model of a thin annular multistart-helical
electron flux taking into account the effect of the quasistatic space-charge field. Plots of the gain and the noise factor
of the traveling-wave gyrotron versus the electrical parameters of the amplifier are obtained.
Zh. Tekh. Fiz. 68, 130–132 (February 1998) 相似文献
979.
H.-J. Scheibe D. Drescher A. Kolitsch A. Mensch 《Fresenius' Journal of Analytical Chemistry》1995,353(5-8):690-694
Morphology and structure of amorphous carbon films deposited with a pulsed arc source (LASER-ARC) have been studied using microscopical methods (SEM, TEM and AFM), electron diffraction and spectroscopical investigation (EELS). The parameters of the arc source and the deposition conditions (substrate temperature) influence morphology and structure of deposited amorphous carbon films. Especially the incorporation and growth of particles, embedded in the film have been investigated. By particle analysis using an optical microscope a majority of particles that is smaller than 500 nm has been determined. The morphology has been also demonstrated similar by AFM and TEM images. Their number and size of particles is strongly influenced by the deposition temperature. The structure of amorphous film is characterized by the EELS-spectra, but the particle structure was not detectable. 相似文献
980.
Summary A new method of evaluating the Tolman cone angle from X-ray structural data available from the Cambridge Crystallographic Data Base has been developed and a statistical analysis of the cone angles of the phosphines PPh3, PMe2Ph, PMePh2, PMe3, PEt3 and PCy3 (Cy = cyclohexyl) in transition metal complexes has been completed. 相似文献