Kossel lines in extremely asymmetric diffraction schemes

It is demonstrated theoretically that the intensity distribution within the Kossel lines in an extremely asymmetric X-ray diffraction scheme has an anomalous shape of a sharp peak exceeding the background intensity by several hundred times. The possibility of experimental observation of this phenomenon is discussed.     

Direct observation of anomalous Kossel lines

Anomalous Kossel lines corresponding to the yield of X rays from a germanium crystal under the conditions of strongly asymmetric diffraction have been observed in the simplest experimental scheme with the use of characteristic Mo K _α radiation and a germanium crystal analyzer. In agreement with the results of a previous theoretical analysis, such lines are narrow collimated beams of radiation in the form of a ridge in a narrow angular range near a given direction whose intensity is one or two orders of magnitude higher than the background with a divergence of about several seconds of arc in the diffraction plane and of about 10′ along the Kossel line. The possible applications of this effect, in particular, for solving the problems of X-ray holography, are discussed.     

Kossel技术中比率方法的改进

本文对Kossel比率方法进行了改进,同时得到一种Kossel定向方法。它能适用于通常用的比率方法不能分析的许多Kossel花样。并且用它分析了Fe-0.76wt％V-0.08wt％N稀合金的随意定向的Kossel花样,其点阵参数精度达5×10^-5?。 关键词：     

Advances in X-ray excitation of Kossel patterns by a focusing polycapillary lens

In this paper, the polychromatic X-ray excitation of Kossel patterns by an X-ray tube and a focusing polycapillary lens will be presented. Additionally, it will be shown that the lateral resolution of the Kossel technique under X-ray tube excitation can be improved and the exposure times can be strongly reduced by using a polycapillary lens. The advantageous combination of X-ray fluorescence and crystal structure analysis by means of Kossel microdiffraction will be demonstrated.     

带电胶体粒子结晶过程的实验研究

利用带电单分散聚苯乙烯胶体粒子，通过自组装机理，制备了体积百分比为4.8%的具有多晶结构的胶体晶体，并用Kossel衍射技术和紫外可见分光光度计分别对晶体的生长过程进行了监测.通过对Kossel的图像分析检测不同阶段相应的晶格结构，发现胶体结晶过程晶体结构演变顺序为由液态—随机层结构—堆无序结构—面心立方孪晶结构到面心立方结构.定量地确定了结晶过程中晶体不同晶面的晶面间距和晶体的晶格常数，通过紫外可见分光光度计测量的晶体透射谱图，计算得到111晶面的晶面间距和晶体的晶格常数，与用Kossel衍射技术得到的结果相一致，还发现随样品放置时间的延长，衰减峰变窄和加深，并向短波方向移动，对应着晶体的晶格常数减小的现象. 关键词： 胶体晶体 自组织 Kossel环 聚苯乙烯粒子     

Kossel lines in angular distribution of X-rays excited by protons in pyrolytic graphite quasi-crystal

Kossel line profiles were experimentally studied upon 1.5-MeV proton excitation of characteristic K _α radiation of argon atoms implanted into an UPV-1T graphite quasi-crystal. It was found that Kossel line profiles depend on argon ion implantation conditions, i.e., the lines generated in crystals implanted at temperatures of 150 and 200°C exhibit different widths and contrasts. In addition to the main Kossel cone line, a second cone line was detected caused by an additional texture component in the UPV-1T pyrolytic graphite quasi-crystal.     

在扫描电子显微镜中所观察到钨的奇异花样

当钨试样倾斜到不同位向以记录一系列电子通道花样时,在<111>方向,<001>方向和<011>方向的准确位置下,观察到一些奇异花样叠加在电子通道花样上。这些奇异花样颇类似于在透射电子显微镜中所观察到的Kossel花样。这种花样具有两个重要性质:(1)花样的强度分布是随着电子能量(电子的加速电压)而改变;(2)花样的几何形貌可以用来描述晶体内部结构的一些特征。最后,从异常散射效应和晶格位与入射电子间相互作用强度a的观点,定性地解释了这种花样的衬度效应来源。 关键词：     

背射Kossel衍射线的指标化

背射Kossel线衍射花样由于各衍射圆锥不共顶点,因此它的指标化有一定困难,特别是对非立方晶系。本文论述两种对立方晶系和非立方晶系都适用的背射Kossel线衍射花样指标化的方法。用本文介绍的极图法或计算机程序方法可以很容易地测定背射Kossel线的衍射指数。第一种方法的特点是简单而且直观;第二种方法自动化程度高,且可以使用误差较大的测量数据。 关键词：     

Anomalous surface photoconductivity in hydrogenated amorphous silicon

The intensity and time dependence of the source-drain photocurrent is measured on hydrogenated amorphous silicon (a-Si:H) field effect transistors as a function of gate bias. The photocurrent increases rapidly, becomes weakly dependent on excitation intensity, and exhibits long decay times. A model in which the relaxation of the space charge dominates the photocurrent quantitatively predicts the experimental data. The results show that anomalous surface photoconductivity is often the dominant photoresponse of a-Si:H.     

Laser pulse reflection by anisotropic plasma

The effect of anomalous amplification of test laser pulse reflected by a nonequilibrium plasma formed under atom ionization by a strong pulse of circularly polarized wave is described. It is shown that the gain in radiation intensity may reach ten orders of magnitude. The most effective amplification takes place for frequencies comparable with the Weibel instability growth rate.     

Behavior of the intensity of galactic and anomalous cosmic rays in the outer heliosphere and large-scale electric fields

The behavior of the intensity of anomalous and galactic cosmic rays in the outer heliosphere is compared. The previous hypothesis, according to which the lowest energy galactic cosmic rays affected by large-scale electric fields far beyond the termination shock wave of the solar wind may contribute to the behavior of the anomalous component intensity, is analyzed.     

Anomalous heating rate effect in thermoluminescence intensity using a simplified semi-localized transition (SLT) model

During thermoluminescence (TL) measurements carried out with different heating rates, one expects the total number of emitted photons to be constant. However, for many luminescence materials one observes a decreased intensity of luminescence at elevated temperatures, due to the presence of the well-known phenomenon of thermal quenching. Recent experimental work on the dosimetric material YPO₄ double doped with lanthanides demonstrated the exact opposite behavior, in which the total luminescence intensity increases with the heating rate during the TL experiments. This anomalous TL behavior was recently explained by using the Mandowski model of semi-localized transitions (SLTs). In this paper it is shown that this anomalous heating rate or “anti-quenching” phenomenon can also be described by using a simplified SLT model of TL with approximated kinetic equations. The simulated glow curves show that as the probability of the non-radiative processes increases, the anomalous heating rate effect becomes dominant. The dependence of the anomalous heating rate effect on the values of the kinetic parameters in the model is examined by allowing random variations of the parameters in the model, within wide ranges of physically reasonable values covering several orders of magnitude. It is shown by simulation that the variable heating rate method can systematically underestimate the value of the activation energy E, while by contrast the initial rise method of analysis almost always yields the correct E value. These simulated results are discussed in relation to recent experimental work on the double doped dosimetric material YPO₄.     

反常色散材料光子晶体中光输运的光学控制

研究了光抽运对由铯原子蒸气构成的光子晶体的影响.研究发现,利用较弱光强的线抽运光即可显著地改变这种反常色散光子晶体的透射率.而利用圆偏振光抽运可以进一步降低抽运光的阈值,并在反常色散光子晶体中获得极大的法拉第旋转.反常色散光子晶体的这些特性为光控光开关的研究和制作提供了一条新途径.     

Anomalous frequency shift in the photoassociation spectrum of a Bose-Einstein condensate

We theoretically investigate the effect of anomalous quantum correlations on the light-induced frequency shift in the photoassociation spectrum of a Bose-Einstein condensate. Anomalous quantum correlations arise because, although formed from a pair of zero-momentum condensate atoms, a condensate molecule need not dissociate back to the atomic condensate, but may just as well form a noncondensate atom pair with equal and opposite momentum, i.e., due to rogue photodissociation. The uncorrelated frequency shift of the photoassociation spectrum is to the red and linearly dependent on the laser intensity I. In contrast, anomalous correlations due to rogue dissociation lead to a blueshifted photoassociation spectrum. For sufficiently low light intensities, the rogue blueshift is dominant and proportional to sqrt[I].     

Anomalous scattered light correlator

The space-time correlation function of the scattered radiation intensity of atoms situated in an external field is investigated. This function includes contributions of the normal +E^–> and anomalous –E–> complex field amplitude correlator. These correlators have components due to scattering by density fluctuations and to collective, diffraction effects. The spatial structure of these correlators is studied and the conditions for the measurement of the anomalous correlator are derived. The temporal properties of the anomalous correlator and the effect of Doppler broadening on the correlation properties of scattered radiation are also considered. The investigation of the anomalous correlator is of interest in high-resolution spectroscopy and may also be useful in the study of nonresonant media.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 70–73, February, 1982.     

Effect of a polar environment on the resonant generation of higher optical harmonics by dipole molecules

An analysis is made of the effect of fluctuations of a polar environment on the resonant generation of higher optical harmonics by dipole molecules in a strong electromagnetic field. The cases of slow and strong fluctuations of the environment are considered. It is shown that the electric fields produced by fluctuating dipole moments of the medium lead to anomalous temperature dependences of the scattered-radiation intensity. In the case of slow fluctuations and some additional conditions, the harmonic intensity exponentially increases with temperature. In contrast, in the case of rapid fluctuations under exact resonant conditions, the harmonic intensity decreases with increasing temperature. Under nonresonant excitation of molecules, a polar medium has no effect on the generation of higher harmonics.     

Quasi-stellar objects as Čerenkov sources

If a beam of ultrarelativistic charges enters a gas cloud ?erenkov radiation may be produced. The condition for such radiation is given, and the ?erenkov power radiated per charge is compared to the synchrotron power. Intense ?erenkov pulses will excite emission lines via stimulated Raman scattering. Due to anomalous dispersion in the presence of ac Stark effect the ?erenkov field will be most intense at frequencies well red-shifted from atomic resonances, and this red-shift will be a feature of the stimulated Raman line emissions. The intensity ratios and anomalous red-shifts of the broad emission lines of QSOs can be explained. ?erenkov emission froma collimated beam will be highly directional. The emission evidently does not occur in BL Lacs, which are pure synchrotron emitters.     

Evidence of anomalous multiplet line shapes in optically thick,laser-produced plasmas

We report observations of anomalous line shapes for the transitions 2p?3d (²P?²D) emitted by the Li-like ions N(V), O(VI), F(VII) in laser-produced plasmas. These transitions are normally doublets but show completely different characteristics (e.g., triplet structures or invension of two-component intensity ratios) in the plasmas. The observed line profiles are accounted for in terms of opacity and Doppler effect produced by plasma expansion. This interpretation is independent of the particular transition involved, i.e., multiplet structures can generate more complicated features with various unexpected new components, anomalous intensity ratios, etc.     

Multiple wave diffraction anomalous fine structure

A new method, multiple-wave diffraction anomalous fine structure, combining the x-ray multiple-wave diffraction and diffraction anomalous fine structure techniques, is proposed. The real part of dispersion correction Deltaf' and fine structure chi function can be obtained directly by multiple diffraction analysis without using Kramers-Kr?nig relations and kinematical fitting of diffracted intensity. Better wave vector sensitivity of the fine structure is expected. The multiple-wave diffraction anomalous fine structure experiment for a GaAs single crystal is reported as an example.     

Temperature Effect of Infrared Rays Absorbed by the Protein Molecules in the Living Systems

The principal features of Infrared absorption of the protein molecules are anomalous red shifts of the main peaks and increases of intensity of the anomalous bands with decreasing temperature which are proved by experiments. We think that these anomalous phenomena are caused by the self-trapping of amide-I vibrational quantum (vibron). We thus proposed a soliton model of the vibrons interacting with optical vibration of amino acid residue (phonon) to study theoretically these phenomena. We find farther out the exponential-reductions of the intensity of the anomalous bands in the infrared absorption with increasing temperature in the protein molecules by using this model. This shows that the living things including human beings and animals can absorb more much infrared lights at low temperature than that at high temperature.