量子电子学简介

一、概况 量子电子学是用量子理论来研究电子器件的一门科学.是无线电电子学的一个新的研究前沿.1955年和1960年微波量子放大器和激光器的相继出现,以及光通讯、能源和材料科学研究的需要,量子电子学得到了飞快的发展,著名的美国电气和电子学工程师学会(IEEE)从1965年开始发行量子电子学期刊,苏联科学院也于1971年开始发行量子电子学刊物.到目前为止,已召开了12次国际量子电子学会议(每两年一次).麻省理工学院等知名学府都开设了量子电子学课程,近十年来,一些有名的教授专家撰写了不少教材和专著.在我国,中国科学院物理所、上海技术物理所…     

CO2激光非线性四频外差探测的实验研究

本文从理论上对巳提出的四频外差探测技术作了阐述,并在实验上实现了非线性四频外差探测,得到了预期的结果.平方律放大器件是四频外差系统电信号处理的关键器件,本文对其原理作了叙述,并依此制成了一实用的器件用于本实验.     

时间域电子自旋共振

时间域电子自旋共振(ESR)是研究顺磁弛豫机理和动力学过程不可缺少的方法,也是提高检测信号的灵敏度和分辨率的重要途径之一。然而,目前在ESR技术中较常用的还是频率域,而时间域ESR(包括付里叶变换法)却远远不如脉冲付里叶变换核磁共振(PFT-NMR)那样迅速的发展。本文对此进行了讨论,认为:如采用与PFT-NMR稍为不同的方法,并在微波技术、快速脉冲电路和电子计算技术等不断改善的基础上,时间域ESR势将成为今后发展的大方向。近年来,在时间域ESR技术方面,最引人重视的是:饱和恢复法和电子自旋回波(ESE)法。本文着重对这两种方法的基本原理、实验方法、应用场合及其优越性和局限性进行了评述。例如,用付里叶变换法(包括二维付里叶变换)把电子自旋回波调制的包络自时间域变换成频率域,从而获得高分辨率的频谱,则可分析出取向或无规取向样品的微弱超精细结构。又如,ENDOR(电子-核双共振)自旋回波与通常的ENDOR相比,前者具有较高的灵敏度以及可检测较低的ENDOR频率等独特之处。此外,文中对瞬态顺磁中间产物的时间分辨ESR和三重态分子在零场中的ESR也分别进行了简短的评介。最后,对时间域ESR发展的远景作了预计。     

光学孤子与全光孤子通信

光学孤子通信是利用光纤中的非线性效应消除脉冲的色散，提高传输码率，最近因掺铒光纤放大器的发展，将取代Ｒａｍａｎ放大器而成为光孤子通信系统中最有效的光放大器，使得光孤子通信进入实用阶段。本文对光学孤子的成形机制，性质以及在光纤通信系统中的应用作了深入浅出的介绍。     

磁共振现象及其应用

近几年来,由于电子学和波谱学的结合,一门崭新的有着极重要的发展前途的学科诞生了。这便是量子电子学。目前量子电子学已经在许多尖端科学技术中显示出它的卓越的作用,例如量子放大器,原子钟等等。共振现象是量子电子学的重要的物理基础。当然,量子电子学所研究的共振现象,并     

光声信号的数字处理

利用数字信号处理技术,可直接应用微机而不用锁定放大器来检测物质的光声信号。本文给出用互功谱技术和多次平均方法所得的一些实验结果。当炭黑和黄色金刚石粉末为试样时,用微机和用锁定放大器所得到的光声信号的相位和幅值都非常吻合。文章还给出了用这数字信号处理技术检测一些薄型不透光试样的热扩散率的实验结果。这些结果与用激光导热仪所测得的结果也良好地相符合。     

固体电子学的发展概况

本文介绍了固体电子学发展的全貌,特别对国际上发展迅速的一些尖端问题和新的动向,作了概括性的说明。文中首先讨论了固体电子学高速发展的客观形势和要求以及它在发展中的特色。把固体电子学的具体内容按固体现象、元件及应用加以概括,并且列举了较重要的电子学系统的固体元件化。全文的重点是讨论固体电子学发展的四大尖端:超快速、超高频、超小型和量子无线电物理,以及一些新的动向。指出元件和线路的统一是整个发展中的特色。在这个趋势下,物理研究、材料器件制备和线路应用将进一步结合起来,其结果将导致新电子学技术向更高阶段迈进。最后总结了目前发展中几个基本性的理论课题。     

由辐射噪声功率估计线性结构振动系统状态,以建立动力学方法论的一种尝试及其模拟实验

本文从系统论的基本观点出发,提出了一种试验方法,叙述了它在环境噪声和振动问题中的模拟,讨论了从伴有其他振动信号和背景噪声的辐射噪声来作非平稳振动结构系统的状态估计。本文的递归估算法是将所谓Bayes定理用正交级数展开后导出的新方法,因此,任何一类状态变量的统计性质都可由此估计概率密度函数推得。由于我们的工作还是初步的,仅限于方法论的观点,所以本方法的可靠性和效用特别通过数字模拟技术作了验证。     

低温放大器组装技术分析研究

本文分析了低温放大器中温度应力影响和质量隐患,从芯片和印制板贴装、引线键合和盒体封装三个方面对低温放大器装配工艺进行了研究,给出了低温放大器组装工艺的关键工序,提出了组装工艺改善方法,对低温放大器的组装技术具有一定参考作用。     

摄像CCD

本文对用作成象传感器的电荷耦合器件(CCD)首先进行了一般性技术介绍。概括了大量的最新文献,涉及到许多物理学特性和电路技术。同时较全面地介绍了主要厂家的产品。对于CCD图象传感器的目前的应用和潜在应用也作了叙述。     

The determination of pair distance distributions by pulsed ESR using Tikhonov regularization

Pulsed ESR techniques with the aid of site-directed spin labeling have proven useful in providing unique structural information about proteins. The determination of distance distributions in electron spin pairs directly from the dipolar time evolution of the pulsed ESR signals by means of the Tikhonov regularization method is reported. The difficulties connected with numerically inverting this ill-posed mathematical problem are clearly illustrated. The Tikhonov regularization with the regularization parameter determined by the L-curve criterion is then described and tested to confirm its accuracy and reliability. The method is applied to recent experimental results on doubly labeled proteins that have been studied using two pulsed ESR techniques, double quantum coherence (DQC) ESR and double electron-electron resonance (DEER). The extracted distance distributions are able to provide valuable information about the conformational constraints in various partially folded states of proteins. This study supplies a mathematically reliable method for extracting pair distributions from pulsed ESR experimental data and has extended the use of pulsed ESR to provide results of greater value for structural biology.     

High-Field and Multifrequency ESR Studies at KYOKUGEN in Osaka University

We have developed high-field and multifrequency (HFMF) electron spin resonance (ESR) apparatus for the magnetic fields up to 65 T at frequencies up to about 6 THz. In addition to this pulsed field ESR apparatus, we are making a multifrequency ESR apparatus with very high sensitivity in a static field. We report the results of ESR studies on BaCoV₂O₈ and NiGa₂S₄, followed by recent developments and future plans of our HFMF ESR apparatus.     

Recent Advances in High-Frequency Electron Spin Resonance Detection Using a Microcantilever

Our recent developments in highly sensitive high-frequency electron spin resonance (ESR) using a microcantilever are reviewed. ESR signals of a Co Tutton salt microcrystal (<1 μg) have been detected at low temperature at frequencies up to 315 GHz under a static magnetic field using a microcantilever and a modulation technique. The achieved sensitivity is about 10⁹ spins/G at 4.5 K. Moreover, we have shown that similar ESR detection using a microcantilever is possible up to 130 GHz under a pulsed magnetic field without using a modulation technique. The achieved sensitivity is about 10¹¹ spins/G at 1.7 K. These results suggest that the ESR detection using a microcantilever is promising for applications to high-resolution and high-sensitivity terahertz ESR.     

Radiation sensitivity and dosimetric features of sultamicillin tosylate: an electron spin resonance study

Particular interest now centers on the preparation of sterile unit-dose preparations. When preparations are purified from microorganisms using classic sterilization techniques, serious degradations may occur, especially in temperature sensitive drugs and drug active components. Sultamicillin is the tosylate salt of the double ester of sulbactam plus ampicillin. Sultamicillin (SULT) tosylate has previously been shown to be clinically and bacteriologically effective in a variety of infections. The use of high-energy radiation, such as gamma rays, for the sterilization of pharmaceuticals offers considerable interest because of the clear advantages this process has compared with other methods of sterilization. However, radiosensitivity of irradiated pharmaceuticals is important in this respect. Thus, radiosensitivity of SULT and its potential use as a dosimetric material were investigated by electron spin resonance (ESR) spectroscopy in the present work. Samples of SULT powder were irradiated at doses of 3, 6, 10 and 15 kGy and ESR spectra were recorded at room and at different temperatures. Variations of different spectroscopic parameters with irradiation dose, temperature and storage time were evaluated using data derived from experimental ESR spectra which exhibited five different resonance peaks. Stabilities of the radiolytic intermediates at high temperatures were also investigated through annealing studies performed at 340, 345 and 350 K. Rapid decreases in resonance peak heights above 325 K were considered a manifestation of the unstable character of the radiolytical intermediates at high temperature, although they decayed relatively slowly at room temperature. Seven different mathematical functions have been tried to fit the experimental dose–response data, and a power function of the applied dose was found to describe best the dose–response data.     

Optical antennas and plasmonics

Optical antenna is a nanoscale miniaturisation of radio or microwave antennas that is also governed by the rule of plasmonics. We introduce various types of optical antenna and make an overview of recent developments in optical antenna research. The role of local and surface plasmons in optical antenna is explained through antenna resonance and resonance conditions for specific metal structures are explicitly obtained. A strong electric field is shown to exist within a highly localised region of optical antennas such as antenna feed gap or apertures. We describe physical properties of field enhancement in apertures (circular and rectangular holes) and gaps (infinite slit and feed gap), as well as experimental techniques measuring enhanced electric vector field. We discuss the analogies and differences between conventional and optical antennas with a projection for future developments.     

Short Time Domain and Double Resonance Techniques in Electron Spin Resonance Spectroscopy

Abstract

In recent years improvements in technology have increased the amount of information obtainable from, and have broadened the areas of application of, electron spin resonance spectroscopy. Some of the techniques that have found wide use in recent years, such as pulse saturation relaxation time measurements, ENDOR and ELDOR, were originally discovered many years ago while others, such as saturation transfer spectroscopy and nanosecond time resolved techniques, are based upon more recent developments. In this review we will survey a number of these techniques, we will explain what they are and what we can learn from them, we will describe some of the spectrometer systems that are required for using them, and we will cite many representative articles which provide further details about them.     

Concepts and methods of ESR dating

Electron spin resonance (ESR) dating is an absolute dating method suitable for the Quaternary which can be applied to a wide range of materials. It is based on determining the natural radiation dose to which a sample has been exposed during its burial period. This paper outlines the basic concepts, and reviews recent studies on the methods and models of ESR dating.

Scope of this paper. This review paper is one of two in this volume providing an overview of recent developments in the field of electron spin resonance (ESR) dating. The paper focuses on studies investigating the fundamental concepts and methods employed in ESR dating, while the companion paper by Rink (this issue) focuses on applications of the method. Previous review articles have been published by Ikeya (1978) and Ikeya (1985), Hennig and Grün (1983), Nambi (1985) and Grün (1989b). Subsequently, papers by Grün (1991), Schwarcz (1994) and Ikeya (1994a); Ikeya (1994b) and Ikeya (1994c) have reviewed specific aspects of the field. There are three books on ESR dating by Ikeya (1986), in Japanese), Grün (1989a)Grün (1989b), in German) and Ikeya (1993), in English) respectively. In view of the coverage of previous reviews of the field, this paper concentrates on research undertaken since 1990.

The first part introduces and outlines the basic ideas of ESR and its application to dating. This is followed by an overview of recent studies concerned with the basic concepts of the field, its methods and models, as independently of specific materials as possible.     

Recent applications of nuclear orientation to solid state physics

This paper reviews how certain problems in solid state physics have been clarified by low temperature nuclear orientation and nuclear magnetic resonance of oriented nuclei. The advantages of these techniques are discussed; a brief survey of recent progress in traditional applications is given; new developments are discussed, and, finally, future trends are suggested.     

磁共振分子影像技术

磁共振分子影像技术是磁共振成像研究领域中最新的发展方向，它是利用磁共振成像为手段来无创伤地研究活体条件下生物细胞内的正常或病理状态下的分子过程的技术. 目前磁共振分子影像技术还处于其发展的初级阶段，但它在临床医学和基础研究中都具有非常广阔的应用前景，因而发展迅速. 文章综述了近几年来国际上磁共振分子影像技术的发展概况，并简要介绍了几类磁共振分子影像常用技术和其中所用到的分子探针.     

Radiation-induced defects in Pr3+-activated Liyf4 laser host

Rare earth doped fluorides have been used in laser applications. Not much is known about the effect of ionizing radiation on the lasing and other properties of fluorides. Therefore, in recent years much attention has been paid to the study of radiation-induced defects in laser materials, as they affect the optical and stimulated emission properties. The defect formation by γ-ray irradiation in Pr³⁺ activated LiYF₄, powder prepared by melt method, have been studied by thermoluminescence and electron spin resonance techniques and are reported in this paper. It is shown that LiYF₄:Pr³⁺ is sensitive to γ-ray radiation. Characterization of this laser material using ESR and photoluminescence techniques is also described.