关键词： 量子阱材料   MBE   光致发光   激光材料   GaAs/AlGaAs   形貌   发光性能  

摘要： 本文介绍了用X射线双品形貌术研究MBE生长的GaAs/AlGaAs量子阱材料中的生长缺陷、位错及其对发光性能的影响。同时研究了低温下MBE生长的GaAs/AlGaAs量子阱材料的正交方向的位错。在有应变超品格过渡层高温生长的量子阱材料中,位错及光致发光性能有明显的改善。

关键词： 气体分子   化学位移   电子能级   SnO2   化学传感   键参数函数   电子集居数   电荷迁移   电导率   量子化学  

摘要： 本文应用键参数函数方法、EHMO方法与从头计算方法研究SnO2的传感作用。计算表明,可由气体分子的前线分子轨道能级初步推测SnO2与这些气体作用引起电导率改变的方向。提出NO被SnO2吸附时,NO的O进入晶格氧空位的物理模型,据此理论计算得到吸附后SnO2的禁带加宽,化学位移方向以及电荷迁移都支持了实验观测。指出SnO2化学传感作用本质上是电荷迁移效应。由于电导率改变与晶格氧空位数目等有关,看来定量检测的化学传感器制备是相当困难的,除非能控制晶格氧空位的数目。

关键词： 霍尔效应   InAs   GaAs   HALL效应   磁学   电子能级   超晶格半导体材料  

摘要： 本文简要地综述了超晶格半导体材料GaAs-Al;Ga;As的物理特性及其在激光和大规模集成电路中的应用,评述了整数量子霍尔效应的主要理论。

关键词： 量子力学   原子物理   厄米算符   定态波函数   原子能级  

摘要： 近代物理概论的第二编是原子物理和量子力学初步,这部分的教学安排和教材处理请参见本刊第一期的课程介绍。在此我们重申两条原则:旧量子论的有关内容已在普物中讲授过,本课程不再要求;本课程简化数学处理过程,将重点放在物理内容上。限于篇幅,本文只着重谈对第二编的基本要求。

关键词： 曝光量   SNR   DQE   感光材料   信噪比   量子效率   激光效率  

摘要： 根据信息论在照相科学中的应用,可以把照相过程看作为传递信息的过程,而感光材料就是一种检测信息和记录信息的介质。近年,随着感光材料在科学摄影方面的广泛应用,人们对感光材料的检测能力愈来愈关心。在60年代初,Marchant和Millikan将检测量子效率(DOE)和信噪比(SNR)的概念应

关键词： Raman scattering   Coherence theory   Light scattering   Molecule scattering   Optical materials  

摘要： The fully quantum mechanical theory of coherent Raman scattering developed in a previous paper [J. Chem. Phys. 70, 4130 (1979)] is extended to include magnetic dipole and electric quadrupole interactions. This is done for radiation of arbitrary polarization. The intensities for the scattering of right and left circularly polarized light from an isotropic sample of optically active molecules are shown to differ slightly. The difference, in many cases, is expected to be of the order of 10^?3 times the coherent Raman intensity. This is of the same order as circular intensity differentials observed in spontaneous Raman spectra. Because of a high signal to noise ratio as well as other advantages, however, it is proposed that coherent Raman scattering may be superior to the spontaneous process for studying Raman optical activity.

关键词： 金属材料   实验值   计算值   检流计   振子   凝固热   热力学性质   熔解热   量子  

摘要： 本世纪物理学的主要目标之一是:根据描述原子质点行为的量子力学理论,来计算所观察到的物体的宏观性能.依靠实验手段,在多数情况下能容易地测出金属材料的硬度、沸点、熔解热、电阻等特性.但如何去建立一些公式来计算这些特性,并能使计算值与实验值相一致,这一直是过去所遗留下来的难题.为了使这些问题能获得进展,作者依据量子力学的基本理论及其计算结果已新建立了计算金属材料多种性能的许多式子,经尽可能收集到的各种数据的验证表明:这些式子的计算值与实验值能令人满意地相符合.本文只简单介绍这些式子中的四个公式.

关键词： Raman scattering   Coherence theory   Correlation functions   Laser beams   Linewidths  

摘要： The fully quantum mechanical theory of coherent hyper‐Raman scattering is developed. In this scattering process, which has previously been proposed, two laser beams of wave vectors and frequencies k₁ and ω₁ and k₂ and ω₂, respectively, impinge upon the sample to produce a scattered beam characterized by a wave vector k₃=4k₁?k₂ and a frequency ω₃=4ω₁?ω₂. An expression for the rate of scattering from a gas is derived, and several polarization experiments are discussed. It is shown that the selection rules for coherent hyper‐Raman scattering are identical to those for the spontaneous hyper‐Raman process. A relation between the coherent hyper‐Raman spectrum and a correlation function of the hyperpolarizability is obtained. The coherent hyper‐Raman process, though not yet observed in the laboratory, may afford an improved way of obtaining hyper‐Raman spectra. This process bears the same relation to spontaneous hyper‐Raman scattering as the coherent Raman process does to spontaneous Raman scattering, and it should display similar advantages, viz., a higher signal to noise ratio and a resolution limited only by the laser linewidth.

关键词： 慢波系统   反演   数学   毫米波段   行波管放大器   行波放大器   刚玉   红宝石   量子  

摘要： 毫米波段,特别是该波段大气衰减率小的那部分,首先是波长接近8毫米的那部分,对射电天文学来说具有颇大的意义。因为在此波段上的混频接收机的噪音温度非常高,那么在其输入端采用象在厘米波段曾用过的量子顺磁放大器便可大大提高辐射计的灵敏度。

关键词： Animals   Factor VIII/analysis   Hemophilia A/blood   Humans   Immune Sera   Macromolecular Substances   Molecular Weight   Platelet Aggregation   Rabbits/immunology   von Willebrand Diseases/blood  

摘要： Antihemophilic factor (AHF, factor VIII) is a macromolecule that can be dissociated into 2 subcomponents. One, of high molecular weight (MW), forms precipitates with heterologous antiserum against AHF and supports ristocetin-induced aggregation of platelets. The other, of lower MW, has procoagulant activity. The plasma of patients with classic hemophilia contains a form of AHF with properties resembling those of the high MW subcomponent. Studies of Hoyer and Breckenridge have suggested that the low MW subcomponent is present in a minority of patients whose plasmas inhibit human circulating anticoagulant antibodies against AHF. Such individuals, CRM+ [cross reacting material], have a species of AHF possessing a nonfunctional variant of the low MW subcomponent. CRM+ hemophilic plasma or serum, like the low MW subcomponent of normal AHF, blocked the inhibitory properties of circulating anticoagulants, in contrast to the high MW subcomponent of normal AHF. A nonfunctional low MW subcomponent was identified in partially purified AHF-like material separated from the plasmas of both CRM+ and CRM- hemophiliacs, the latter being patients whose plasmas do not neutralize circulating anticoagulants. This low MW subcomponent, like that of normal AHF, inhibited antiserum against the normal low MW subcomponent, but not antiserum against the normal high MW subcomponent. The defect in the hemophilic plasmas tested was probably not associated with the absence of the low MW subcomponent of AHF.