《近代物理学中重大发现的再探索》连载⑨——探究原子内部的奥秘(下)

以再探索的方式重现了人们认识原子内部运动规律,构建玻尔原子理论的过程,具体介绍科学探究中创立与发展科学理论的方法,以培养大学生的创新能力.     

类氢原子中电子椭圆轨道量子化的一个简化推导

利用能量守恒，角动量守恒及椭圆轨道的几何性质，结合玻尔－索末菲量子化条件，对类氢原子中电子的椭圆轨道与能量公式给出了一个简化的推导。     

玻尔的并协原理与我国古代阴阳学说

本文介绍了玻尔的并协原理和我国古代阴阳学说的基本内容 .1 947年玻尔授勋时 ,他选择了太极图作为礼仪罩袍的图案 ,表明我国古代文明与现代科学之间存在着深刻的和谐一致     

封面说明

我们在本刊今年的封面上,纪念卢瑟福和玻尔这两位物理学大师先后相承的工作(即卢瑟福的原子结构的行星模型和玻尔的量子化的原子结构理论)以及他们二人的结识、合作百年.     

玻尔（Bohr，niels Henrik Dayid，1885—1962）丹麦物理学家（Physicist，Denmark）

他在普朗克量子假说和卢瑟福原子行星模型的基础上，于1913年提出了氢原子结构和氢光谱的初步理论。稍后，又提出了“对应原理”（在物体大、运动范围广的极限情况下，微观运动规律应该趋近于宏观运动规律；并且两种规律应该具有相互对应的关系）。这些工作，对量子论和量子力学的建立起了重要作用。此外，玻尔在原子核反应理论和解释重核裂变现象等方面，也有重要的贡献。     

朋原子结构与原子辐射理论看玻尔新思维的特征

玻尔提出原子理论过程中的创新思维具有显著的开放性、批判性、辩证性和非逻辑性特征，对当前的科技创新和科学教育有重要的启迪，促使我们对摆脱旧有观念束缚、充分利用直觉思维、恰当处理精确与的关系等问题进行了深入的思考。     

玻尔理论的比较研究--纪念玻尔理论诞生90周年

本文回顾了玻尔理论，系统地分析了玻尔理论和经典理论、量子力学之间的联系与本质区别，简要论述了玻尔理论对物理学发展的贡献与历史地位。     

玻尔理论学习中常见的几个误解

玻尔原子模型在解释氢原子光谱时取得了巨大的成功，因此，高中物理教材第三册(必修加选修)“量子论初步”一章中，有关玻尔理论的习题都是关于氢原子的讨论和计算．初学玻尔理论，往往产生一些误解，本文就常见的几个误解进行讨论．     

玻尔的对应原理及其推广

以玻尔对应原理所形成的思想过程为历史背景，从三个方面论述了该原理的深刻科学内涵以及它对哥本哈根学派的深刻影响．作为一种富有启发性的科学思想，玻尔对应原理对当今物理学的发展及科学研究仍具有极为重要的指导作用．     

高中物理“氢原子光谱与玻尔模型”的教学尝试

利用分光计、三棱镜,将氢原子光谱呈现在高中物理课堂.利用光栅,准确测量谱线波长,并引导学生得到巴尔末公式,进行深入思考.将玻尔理论进行系统教学,用理论解释实验,得到了很好的教学效果.在本课中,弥补了学生对于氢原子光谱实验现象的缺失,也弥补了教材对于玻尔理论系统性的缺失.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.