Comparative analysis of characteristic electron energy loss spectra and inelastic scattering cross-section spectra of Fe

The inelastic electron scattering cross section spectra of Fe have been calculated based on experimental spectra of characteristic reflection electron energy loss as dependences of the product of the inelastic mean free path by the differential inelastic electron scattering cross section on the electron energy loss. It has been shown that the inelastic electron scattering cross-section spectra have certain advantages over the electron energy loss spectra in the analysis of the interaction of electrons with substance. The peaks of energy loss in the spectra of characteristic electron energy loss and inelastic electron scattering cross sections have been determined from the integral and differential spectra. It has been shown that the energy of the bulk plasmon is practically independent of the energy of primary electrons in the characteristic electron energy loss spectra and monotonically increases with increasing energy of primary electrons in the inelastic electron scattering cross-section spectra. The variation in the maximum energy of the inelastic electron scattering cross-section spectra is caused by the redistribution of intensities over the peaks of losses due to various excitations. The inelastic electron scattering cross-section spectra have been analyzed using the decomposition of the spectra into peaks of the energy loss. This method has been used for the quantitative estimation of the contributions from different energy loss processes to the inelastic electron scattering cross-section spectra of Fe and for the determination of the nature of the energy loss peaks.     

New opportunities for quantitative analysis as applied to reflected electron energy loss spectroscopy of Fe/Si structures

The feasibility of determining the elemental composition, chemical state, and element distribution across the depth in a subsurface region using the computer simulation of the electron inelastic scattering cross section is demonstrated with iron layers on silicon substrates. Analysis is carried out based on the dielectric theory and on the experimental determination of the product of the electron inelastic mean free path by the inelastic scattering cross section from reflected electron energy loss spectra.     

Electron spectroscopy of iron disilicide

We have reported on the results of a complex investigation of iron disilicide FeSi₂ using characteristic electron energy loss spectroscopy, inelastic electron scattering cross section spectroscopy, and X-ray photoelectron spectroscopy. It has been shown that the main peak in the spectra of inelastic electron scattering for FeSi₂ is a superposition of two unresolved peaks, viz., surface and bulk plasmons. An analysis of the fine structure of the spectra of inelastic electron scattering cross section by their decomposition into Lorentzlike Tougaard peaks has made it possible to quantitatively estimate the contributions of individual energy loss processes to the resulting spectrum and determine their origin and energy.     

Scattering of excitons by excitons in semiconducting quantum well structures

We have theoretically investigated the scattering of excitons by excitons in a two-dimensional semiconducting quantum well system. The scattering cross sections have been calculated using the Born approximation for both the elastic and inelastic scattering of the excitons by excitons. The threshold for inelastic scattering is increased over the value in a bulk semiconductor because of the enhancement of the exciton binding energy by its confinement. The behavior of the scattering cross section as a function of the energy of relative motion of the excitons is different than in the bulk and the cross section is a more sensitive function of the ratio of the electron and hole masses than in the bulk.     

20MeV以下快中子与56Fe非弹性散射截面的分歧研究

56Fe的非弹性散射截面在核装置中子输运计算中扮演着重要的角色,但无论从实验数据还是从评价数据,非弹性散射截面都存在很大分歧,它的数据直接影响到核装置的设计、建造与运行维护。本工作从实验数据本身出发,深入分析了不同实验室测得的847 keV的γ产生截面的分歧,经转化后补充非弹性散射截面的实验空白能区,并同时利用满足全截面、去弹截面等截面自洽关系的评价方法推荐了高精度的快中子与56Fe的非弹反应截面结果。积分检验表明,新的非弹截面的改进使得评价数据与积分实验结果一致,较CENDL-3.1的评价数据结果有显著改善。Knowledge about the inelastic scattering cross section of 56Fe is very important in neutron transportation calculation. However there are great discrepancies not only between experimental data but also between evaluated data. More detail analysis was performed for inelastic scattering cross section in the fast range up to 20 MeV where there are significant differences among the main evaluated libraries, mainly caused by the different inelastic scattering cross section measurements. The large discrepancies on 56Fe(n, n₁'γ) cross section which could fill the neutron energy blank of the 56Fe(n,inl) were clarified and were converted to the inelastic scattering cross section of 56Fe. And the high-quality results were evaluated by using the unitarity constrain among total cross section, noelastic reaction and other reactions. The integral experiment result indicates that the new evaluated result of inelastic cross section brings greater improvement than that of CENDL-3.1.     

Tagged-photon events in polarized deep inelastic scattering

Deep inelastic scattering events of a longitudinally polarized electron by a polarized proton with a tagged collinear photon radiated from the initial-state electron are considered. The corresponding cross section is derived in the Born approximation. The model-independent radiative corrections to the Born cross section are also calculated. The obtained result is applied to the elastic scattering.     

Cross section of inelastic polarized neutron scattering by superconducting rings

A general expression for the cross section of inelastic magnetic scattering of cold polarized neutrons by superconducting rings has been derived. In this scattering process, the metastable superconducting current changes via quantum jumps corresponding to a decrease in the number of fluxoids in the superconducting ring by one or several units and the change in the energy of the ring is transferred to the kinetic energy of the scattered neutron. For rings from type-II superconductors with a thickness smaller than the field penetration depth but larger than the electron mean free path, the cross sections of inelastic scattering with neutron spin flip have been obtained for the first time. The possibility of increasing the cross section of neutron scattering by a system of rings has been discussed.     

Background subtraction in electron spectroscopy by use of reflection electron energy loss spectra

The use of reflected electron energy loss spectra (REELS) in deconvoluting the inelastic background signal from XPS and AES spectra from homogeneous samples is studied. It is demonstrated that under certain assumptions, the cross section for inelastic electron scattering can be extracted from a REELS spectrum. This cross section is applied to deconvolute an experimental XPS spectrum of aluminium. The method, its limitations and its relation to other methods are discussed.     

Inelastic scattering of charged particles by atoms using the Thomas-Fermi statistical method

We describe a method of calculating the differential cross section for the inelastic scattering of charged particles by atoms based on the statistical model of the atom. For the most general form of the potential of the atom we obtain an analytical expression for the differential (with respect to the energy of the electron ejected from the atom) cross section of inelastic scattering. It is shown that the statistical method of Thomas-Fermi is applicable when the energy of the ejected electron is sufficiently high.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 92–96, September, 1986.     

Theory of inelastic neutron scattering of metallic electrons in one-electron approximation

The cross section is studied for the inelastic magnetic scattering of epithermal neutrons by electrons in a metal where the states for the electrons are described by band theory. If the ratio between the wave number of the electrons and the wave number of the incoming neutrons is small compared with unity but not smaller than the mass ratio between electron and neutron, it is possible to calculate the cross section in the vicinity of certain scattering angles more closely. By such experiments one could obtain some information about the diameter of the Fermi surface and the mass tensor of the electrons.     

Electron-cluster interactions

Beam depletion spectroscopy has been used to measure absolute total inelastic electron-sodium cluster collision cross sections in the energy range fromE0.1 toE6 eV. The investigation focused on the closed shell clusters Na₈, Na₂₀, and Na₄₀. The measured cross sections show an increase for the lowest collision energies where electron attachment is the primary scattering channel. The electron attachment cross section can be understood in terms of Langevin scattering, connecting this measurement with the polarizability of the cluster. For energies above the dissociation energy the measured electron-cluster cross section is energy independent, thus defining an electron-cluster interaction range. This interaction range increases with the cluster size.     

Azimuthal dependence of forward-jet production in DIS in the high-energy limit

As a signal for the BFKL Pomeron in small-x deep inelastic ep scattering, we calculate the azimuthal dependence of the inclusive cross section of forward jets relative to the outgoing electron. For not very large differences in rapidity between the current jet and the forward jet the cross section peaks at π/2. For increasing rapidity BFKL dynamics predicts a decorrelation in the azimuthal dependence between the electron and the forward jet.     

Deconvolution of inelastic background signal from XPS spectra of homogeneous solids

For noble and transition metals, the product of the inelastic electron mean free path and the differential inelastic scattering cross section is a weak function of both the particular metal and the electron energy. It is demonstrated that this property can be useful in the removal of inelastically scattered electrons from XPS spectra of homogeneous solids.     

Coupling to the elastic channel in electron impact spectroscopy: A simple second born model and its application to excitation of the 61P1 state of mercury and to the excitation of molecules

The matrix element in the infinite channel close coupling approximation responsible for coupling to the elastic channel in electron impact inelastic encounters is investigated. The contribution from the imaginary part of the energy denominator in the elastic coupling matrix element for dipole allowed transitions is shown to yield large angle differential cross sections in good agreement with experiment. This coupling mechanism predicts that the shape of the inelastic differential cross section will be dominated by the shape of the elastic cross section in the large angle high energy limit. In fact the coupling matrix element exhibits a dependence on incident energy, k², and momentum transfer, K, of the form 1/kK² which is in agreement with the theoretical predictions of Huo and means that in the limit of high incident energy the non-first-Born elastic coupling will dominate the angular dependence of the inelastic differential cross section at large scattering angles. In the case of molecular electron impact spectra it is shown that the analog of the Massey—Moore coherence features depending on the symmetry of the states involved in the excitation process will also occur in the coupling contribution. It is suggested that this new mechanism for producing coherent features in inelastic differential cross sections may be the explanation of the coherent features observed experimentally by Karle and Swick.It can be concluded on the basis of the results obtained here that the coupling to the elastic cross section provided by the imaginary contribution from the second Born energy denominator is sufficient to explain presently available experimental data on the large angle differential cross section and spin polarization. The simple coupling model was found to be inadequate to explain the small angle differential cross section in the range 10° < θ < 30° even at incident energies as high as 400 eV. The calculations also showed significant differences between first and second Born calculations at zero scattering angle. No conclusion can be drawn about this observation as all the omitted terms should make significant contributions in the small angle region. It is important to again emphasize that the large angle scattering even in the limit of high incident electron energy will be completely dominated by the coupling to the elastic channel^{7, 11}. On the basis of this work it appears that the coherent structure in the large angle inelastic differential cross section observed by Swick and Karle^{12, 13} at incident electron energies in the keV region may well be due to coupling to the elastic channel.     

Inelastic interactions of fast nucleons with nuclei and fission of nuclei

The cross section for the fission of actinide nuclei that is induced by fast neutrons is considered as a fraction of the cross section for inelastic nucleon interaction with nuclei. In turn, inelastic nucleon interaction with a nucleus is treated as scattering on intranuclear nucleons. It is shown that this interaction model describes satisfactorily the cross section for the inelastic interaction of 60- to 2200-MeV nucleons for a broad set of nuclei and that the energy dependence of the cross section for the fission of actinide nuclei that is induced by 400- to 1000–MeV protons replicates the energy dependence of the cross section for inelastic interactions with respective nuclei. From the model used, it follows that the cross sections for proton-nucleus interactions exceed cross sections for respective neutron-nucleus interactions in the energy range extending up to 550 MeV; at higher energies neutron cross sections are larger than proton cross sections.     

He-Na2体系低温下的冷碰撞研究

在已经拟合好的He-Na₂体系势能面上,根据原子-双原子分子的非反应性碰撞动力学的相关基本理论,在空间固定坐标系下,采用严格的密耦方法求解了He原子和Na₂分子的转动非弹性碰撞动力学方程.并对He-Na₂体系的微分散射截面、积分截面作了详细的分析,结果与实验符合得比较好.结果表明：（1）弹性散射（Δj=0）截面远大于非弹性截面;（2）较小Δj的跃迁主要产生前向散射,随着Δj的增加,后向散射的几率增加 关键词： 2体系')" href="#">He-Na₂体系 密耦方法 微分散射截面 积分截面     

Electron impact ionisation cross sections derived from total inelastic cross section for CF3X and CF2X2 (X = H,Cl, Br and I) molecules

We report here the total ionisation cross sections for CF₃X and CF₂X₂ (X = H, Cl, Br and I) molecules by electron impact from ionisation threshold to 5 keV. The total inelastic cross section is obtained employing a quantum mechanical approach called spherical complex optical potential formalism. Then, using a semi-empirical complex scattering potential-ionisation contribution method, the ionisation cross section is derived from the inelastic cross section. The results obtained are compared with previous measurements and theoretical values, wherever available and a satisfactorily agreement is observed. The ionisation cross section values for CF₂I₂ molecule are reported for the first time.     

Theory of scattering of electromagnetic waves of the microwave range in a turbid medium

The coefficient of extinction of electromagnetic waves of the microwave range due to their scattering from clusters suspended in an amorphous medium and responsible for turbidity is calculated. Turbidity resembles the case when butter clusters transform water into milk. In the case under investigation, the clusters are conductors (metallic or semiconducting). The extinction coefficient is connected in a familiar way with the cross section of light scattering from an individual cluster. A new formula is derived for the light scattering cross section in the case when damping of oscillations of an electron is due only to spontaneous emission of light quanta. In this case, the resonant scattering cross section for light can be very large. It is shown that this can be observed only in a whisker nanocluster. In addition, the phonon energy on a whisker segment must be higher than the photon energy, which is close to the spacing between the electron energy levels in the cluster.     

考虑到原子中电子运动的氢原子─电子的Glauber散射理论

在Ｇｌａｕｂｅｒ理论的基础上，考虑到原子内部的电子运动对于象ｅ－Ｈ的弹性和非弹性散射截面计算的影响。理论计算表明，原子内部电子的运动对于ｅ－Ｈ的弹性散射截面影不大，而对于非弹性散射截面有着一定的影响。     

Measurement of cross sections for inelastic cold-neutron scattering in metals and polymers by the method of (<Emphasis Type="Italic">n, γ</Emphasis>) analysis

The results obtained by measuring the cross sections for the inelastic scattering of very cold neutrons for a number of metals and polymers by the method of a neutron-irradiation analysis are presented. The method is based on simultaneously measuring events of inelastic scattering and neutron capture in the sample under investigation via recording gamma radiation with a semiconductor germanium detector. Neutron capture by a nucleus of the sample is accompanied by the prompt radiation of gamma rays having a known spectrum. Upon inelastic scattering, a neutron acquires thermal energy. Upon leaving the sample, this neutron is absorbed in a special converter that contains the isotope ¹⁰B. The capture of the neutron by a ¹⁰B nucleus is followed by the emission of a 477-keV gamma ray. The probabilities of capture and inelastic scattering are proportional to the respective neutron-interaction cross sections, and the ratio of the recorded detector counts corresponding to events of the two types does not depend on the spectrum of the incident flux of very cold neutrons or on the trajectory of neutron motion in the sample. The sought inelastic-scattering cross section at a fixed sample temperature is calculated by using this ratio and the known cross section for neutron capture by the sample isotope having a known gamma-radiation spectrum.