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961.
表面分形球、柱的光散射 总被引:2,自引:0,他引:2
分形和分维是近些年才兴起的一门处理复杂事物的新方法 ̄[1]。本文主要研究具有表面分形的球、柱的光散射特征。我们首先利用几何光学近似研究了一种表面满足自仿射原理的分形均匀球的散射,其散射特性与分维存在一定的关系。我们还利用微扰法讨论了表面具有沟槽的分形柱的光散射的分形特征。 相似文献
962.
本文从实验的角度介绍从薄膜导波传播衰减研究光学薄膜损耗的方法,并以一些低损耗的光学薄膜样品的测量结果说明这种方法对损耗研究的灵敏程度及其优越性. 相似文献
963.
用后向散射压缩器产生超高强度激光 总被引:1,自引:0,他引:1
报道自制的一台小型的激光系统,用后向布里渊散射与光栅压缩系统组合,把5ns激光脉冲压缩到40ps,压缩率大于100倍. 相似文献
964.
Summary In this paper we present a vibrational-spectroscopy technique which combines the advantages of coherent anti-Stokes Raman
spectroscopy (CARS) and linear Raman difference spectroscopy. The method which we call CARS difference spectroscopy can be
applied for the study of small frequency shifts and/or bandwidth changes in the CARS spectra of liquid mixtures and solutions.
First we develop the theory necessary for the interpretation of experimental data obtained from CARS difference measurements
of mixtures of two Raman-active liquids and present some model calculations for benzene-toluene mixtures of different concentrations.
Then the experimental arrangement used for CARS difference measurements as well as some examples of recorded spectra are described.
We show that it is possible to observe the effects of dilution on CARS spectra with high accuracy by applying the discussed
technique.
Paper presented at the “XI European CARS Workshop”, Florence, Italy, 23–25 March, 1992. 相似文献
965.
The effect of change in deuteron size on its elastic scattering from protons and alphas is investigated by varying the Hulthen
parameters of the deuteron wave function in the scattering process. The cross sections forp-d scattering, calculated in the Born approximation, are found to increase substantially at backward angles even when the deuteron
size is reduced by a small amount, whereas the shape of the angular distribution does not change significantly. For theα-d elastic scattering, interaction potential is obtained by folding the deuteron wave function and the optical potential for
nucleon-scattering. The cross sections calculated atE
d
= 13·7 MeV, shows that the first minimum around Θcm = 60° is deepend as the deuteron size is reduced, while at 52 MeV bombarding energy, the size effects are not very distinct.
These observations are useful in the interpretation of deuteron cluster knockout reactions. 相似文献
966.
The phonon dispersion curves for aluminium arsenide and antimonide have been investigated by using a deformation bond approximation
model. The results obtained from this model are compared with the experimental values wherever it is available. Since there
is no complete experimental phonon dispersion curves for AlAs, we could not compare our calculated results, but the results
of AlSb have been compared with the inelastic neutron scattering measurements at 15 K. However, we compare the phonon frequencies
of AlAs and AlSb at critical points of the Brillouin zone obtained by our calculations and Raman spectroscopy measurements.
This model predicts the phonon modes satisfactorily in all the symmetry directions of the Brillouin zone (BZ). The spectrum
has similar features as observed in other III–V compound semiconductors. 相似文献
967.
Metal-containing amorphous hydrogenated carbon films are of high interest for industrial applications because of their excellent frictional properties, their high abrasive wear resistance and their electrical conductivity, which can be adjusted in a range of 10–12 orders of magnitude. In order to get insight into the mechanical and electrical properties it is necessary to study the nanostructure of the films. The structure consists of small nanometer sized metallic or carbidic particles, which are embedded in a three dimensional amorphous hydrogen-carbon matrix. Anomalous small angle X-ray scattering (ASAXS) and scanning tunneling microscopy (STM) have been used to determine size- and distance-distributions of the particles as a function of metal content. Problems and restrictions of both methods will be discussed. Furthermore the capabilities of scanning probe techniques to distinguish different materials on a nanometer scale (material contrast) have been studied employing barrier height imaging (dI/dz) and friction force microscopy.Dedicated to Professor Dr. rer. nat. Dr. h. c. Hubertus Nickel on the occasion of his 65th birthday 相似文献
968.
根据中子与天然Zr及其同位素反应的总截面,去弹截面和弹性散射角分布的实验数据,得到一组普适的光学模型势参数;应用得到的光学模型势参数,光学模型,Hauser-Feshbach理论,预平衡反应的激子模型和扭曲波玻恩近似理论,系统计算和分析了中子与90,91,92,94Zr反应的非弹散射角分布和双微分截面,理论结果与实验很好的一致. 相似文献
969.
M.A. Muñoz-Márquez 《Surface science》2004,565(1):1-13
The oxidation of Ni(1 0 0) and Ni(1 1 1) at elevated temperatures and large oxygen exposures, typical of the methods used in the preparation of NiO(1 0 0) films for surface studies, has been investigated by medium energy ion scattering (MEIS) using 100 keV H+ incident ions. Oxide film growth proceeds significantly faster on Ni(1 1 1) than on Ni(1 0 0), but on both surfaces oxide penetration occurs to depths significantly greater than 100 Å with total exposures of 1200 and 6000 L respectively. The metal/oxide interface is extremely rough, with metallic Ni extending to the surface, even for much thicker oxide films on Ni(1 1 1). On Ni(1 1 1), NiO growth occurs with the (1 0 0) face parallel to the Ni(1 1 1) surface and the close-packed 〈1 1 0〉 directions parallel. On Ni(1 0 0) the MEIS blocking curves cannot be reconciled with a single orientation of NiO(1 0 0) (with the 〈1 1 0〉 directions parallel) on the surface, but is consistent with the substantial orientational disorder (including tilt) previously identified by spot-profile analysis LEED. 相似文献
970.
Using a right-angled magnetic air prism, we have achieved a separation of ~10 arcsec between ~2 arcsec wide up and down-spin peaks of 5.4 Å neutrons. The polarised neutron option has thus been introduced into the SUSANS instrument. Strongly spindependent SUSANS spectra have been observed over ±1.3 × 10?4 Å?1 range for several magnetic alloy samples. Spatial pair-distribution functions for the up and down-spins as well as the nuclear and magnetic scattering length density distributions in the micrometer domain, have been deduced from these spectra. 相似文献