Особенности излучательных свойств квантово-размерных частиц узкозонных полупроводников

For colloidal quantum-size particles (QP) of narrow-gap semiconductors, in contrast to quantum dots of wide-gap CdSe, in QP-PbS there take place an anomalous temperature dependence of the photoluminescence intensity. Also, in the planar microstructure containing QP-InSb, long-wavelength radiation (more than 3 µm) and photoconductivity (over 20 µm) was observed. Under certain conditions, the radiation intensity and photoconductivity demonstrate a resonance maximum. The effects were explained in the model of a one-dimensional quantum oscillator, which energy substantially depends on the effective mass of its quasi-free electron. This leads to competition between the manifestations of long-wave radiation and photoluminescence, and hence, to the anomalous temperature dependence of photoluminescence. It is assumed that QP-InSb in a planar microstructure can be sources and receivers of terahertz radiation, which properties depend on the crystal structure of quantum-sized particles determined by the parameters of their synthesis.

Resonance effect for strong increase of fusion gains at thermal compression for volume ignition of Hydrogen Boron-11

An anomalously strong increase of nuclear fusion gains for laser driven compression and thermal ignition of hydrogen-boron11 has been discovered from computations by using the latest results of Newins and Swain about details of a resonance maximum of the astrophysical S-function at 148 keV for the reaction cross-sections. Extensive computations based on volume ignition showed some usual improvements of the fusion gains. However, for a very narrow range of parameters, the increase of the gain was found to be higher by more than a factor 6. This is very unusual in all similar computations and is related to retrograde properties which were known for other parameter values. On top it is most important that the anomalous range is in the practically very interesting range for incorporation of laser pulse energies of few megajoules. The gains of up to 20 may be of interest for power generation in future by the high density fusion scheme.

On the reliability problems of structures subjected to dynamical loads

Mechanically, the assessment of the structure's safety relates to three aspects: strength, stability and oscillation. In the oscillation problems of structures, the safety conditions are conditions of frequency, amplitude, resonance, maximum displacement,etc ...In case that the structure itself contains random parameters and subjects to external loads that are also the random parameters (or random processes), the assessment of the structure's safety according to the deterministic inequalities of structural mechanics will be insignificant. Therefore, this should be assessed according to the probabilistic point of view, namely, according to the reliability.The determination of reliability of the oscillation problems of structures encounters many difficulties because the outputs of the structural analysis problem are the random processes (or the random field). Meanwhile, up to now, the determination of a probability according to which a random process will belong to a given domain by mathematical method has not been sufficiently studied yet.In this paper, the authors, originating from a general definition on the reliability of a system by V. V. Bolotin, assess the reliability of oscillating structure, by determining the upper and the lower bounds of the reliability.The upper and the lower bounds of the reliability are recommended to be determined by determining the probability depending on only an inequality instead of determining the it depending on a system of inequalities. Thus, the determination is very favourable.

Resonanzeinfang langsamer Elektronen in Äthan und Propan

By means of a time-of-flight method the electron drift velocity ν_ in ethane was measured at densities between N = 1,5 · 1019 and 1,1 · 1021 cm-3 (450 Torr ≦p20 ≦ 33390 Torr). Below E/N = 10-18 and above E/N = 10-16 Vcm2 (E/p20 < 0,03 and > 3,3) ν_ is independent of density N, in the intermediate region ν_ decreases at a given E/N with increasing density. This means a violation of the similarity rule. As function of E/N at a given X the relative drift velocity q = ν_ (p)/v (450 Torr) shows a resonance curve with a minimum at E/N = 6,5 · 10-18 {E/p20 - 0,2). This effect can be described, assuming that the electron is attached to the C2H6- molecule for a short time τ. The cross section for the electron attachment, Qa, has a resonance maximum at electron energies of ~ 80 meV. Qa is shown to be ≦ 10-15 cm2 and the life time to be ≦ 10-14 sec. - In propane a similar density-effect is found.

Die Hochfrequenz-Resonanz-Sonde

Dc and ac currents to a rf resonance probe were investigated experimentally in the frequency range from 1 to 100 Mc/s in a quiescent Cesium plasma. The measurements in the plasma are explained by calculations and measurements with a lumped-constant equivalent network (“plasma simulator”).It is shown that the ac current to the probe is strongly influenced by the capacitance of the cable leading to the probe. A device to compensate this cable-capacitance is developed and used. Furthermore, it is shown for the first time that the double (or devided) main resonance maximum, occurring frequently with dc and ac currents to the resonance probe, is generally due to the influence of a second reference electrode.A simple and direct (“focus”) method for very precise plasma density determination (from the intersection point of the rf-current-vs.-frequency curves with probe voltage as parameter) is developed and compared with ac transmission current and LANGMUIR probe measurements at plasma densities between 2 × 106 and 3 × 107 cm–3. Agreement is obtained between these three experimental methods within their margins of error. The comparison leads to a better understanding of the measured LANGMUIR characteristic and of the Cs-plasma of the “Alma I” device.

Resonance phenomena in the scattering of α -particles by some light nuclei

The early experiments of Chadwick and Bieler (1921) and Rutherford and Chadwick (1927) showed that it was possible, in the case of light nuclei, to observe deviations from the classical-coulomb scattering laws by using the α -particles from radioactive sources. The departure from the classical scattering was found to be most marked at large energies, the ratio of the actual to the classical scattering appearing to increase very rapidly with energy for the most energetic particles used. Later experiments by Riezler (1932, 1935) extended these early observations, but also showed that in one case, the large angle (150°) scattering by carbon, the departure from classical scattering does not become uniformly greater for increasing energy of the α -particle, for large α -particle energies, but shows a marked maximum at 5 MeV. This result was subsequently interpreted by Wentzel (1934) as a resonance phenomena. In the experiments of Riezler the resolution with respect to energy of the scattered particles was rather low. In addition the scattering was not observed at a sufficiently large and closely spaced series of energies to decide whether or not the ratio to classical scattering did increase continuously with increasing α -particle energy, for very fast particles, in cases other than carbon. In the case of carbon itself, the maximum in the scattering ratio was rather broad (about 1 MeV) and it was not possible in view of the low resolution of the experiments to decide the real width of the resonance maximum. Since the experiments described here were carried out, observations of the scattering of α -particles in oxygen and neon have been published by Brubaker (1938). In both these cases resonance phenomena are in evidence, but even in these experiments the resolution with respect to energy was not very high and the spacing of the observations not as close as is desirable.