三次谐波的再吸收和AC Stark效应对CO的三光子共振多光子电离光…

本文报道了三光子共振条件下ＣＯ的Ａ＾１П←Ｘ＾１Σ＾＋跃迁的多光子电离光谱。并研究了谱线强度的反常压力效应以及谱线的位移和不对称加宽。通过园偏振激光实验，证实了此光谱来源于ＣＯ分子吸收其自身介质中的激光诱导的三次谐波；并利用相位匹配条件在理论上解释了实验中所观察到的谱线强度的反常压力效应。与此同时，研究了ＡＣＳｔａｒｋ效应引起的谱线位移和不对称加宽。并首次对此效应进行了定量计算，其结果和实验观测值     

基于激光共振电离质谱的钆奇宇称高激发态研究

钆同位素可作为生产医用同位素¹⁶¹Tb等的靶材,受限于高效光电离路径缺失等问题,目前仅能通过电磁方法生产,为实现钆的多步光电离,需要获取高激发态等光谱数据.基于国内自主研发的高分辨激光共振电离质谱,利用双色三步光电离方案,扫描了钆的36900～37700 cm^-1能区,首次获取了7条奇宇称高激发态能级,能级位置准确度可达±0.1 cm^-1,并根据角动量选择定则确定了可能的J值,同时发现了可用于质谱性能检验的单色光电离谱线.     

钠蒸气中的双光子共振三光子电离和双光子混合共振三光子电离

在钠原子－分子混合样品中，分别运用双光子共振三光子电离以及双光子混合共振三光子电离，测得了钠原子４Ｄ态的电离流时间衰减曲线。由电离流与多光子动力学参数的关系，得到了４Ｄ态的光电离截面。     

用激光共振电离光谱测定铈原子奇宇称高激发态(Ⅰ):32 042～34 575 cm-1

激光共振电离光谱是一种十分适合于高能量区重元素复杂原子结构研究的技术。为寻找原子最佳的共振电离通道，利用这一技术对铈原子奇宇称高激发态进行了研究。在32042－34575cm^-1范围内，用两步共振激发和非共振电离方法，首次观察到了83条铈原子奇宇称高激发态能级，测量了这些新能级的能量和给出了可能的总角动量J值。     

“波长等效激光”作用下铀原子的单色三光子共振电离谱测量

用Nd:YAG532nm激光泵浦的混合染料激光得到了在相当于铜蒸气激光器泵浦染料激光的某个波段上增强的激光输出，测得了铀原子在562-586nm波段内的单色三光子共振电离谱中140个能级，其中575.814和575.836nm两个峰很好地分开了，它们的相对强度也能测定，若用单一染料的激光是难以做到，因为目前尚无合适的染料在上述波段内能有强的激光输出。     

原子多步电离过程中激光功率配置理论研究

从速率方程出发,从理论上研究了原子多步电离过程中激发和电离激光的功率密度合理配置问题.对典型三步三光子电离过程的计算结果表明:在总泵浦激光功率一定条件下,存在一个最佳的激光功率分配方式,这个最佳激光功率分配对应着最高的原子电离几率.给出的结果与以往从饱和激发条件得出结果有很大不同.这里所采用的方法可以推广到更复杂的原子多步激发电离情形.     

探测大气污染源的新方法——激光质谱法

此文介绍了大气污染源检测的新方法 -激光质谱法的原理、特点和近几年作者所在课题组在研究大气污染分子方面的成果以及正在开展的应用激光质谱法测汽车、摩托车尾气的工作。     

2-乙氧基苯腈的激发态和离子态光谱

首次报道了2-乙氧基苯腈的双色共振双光子电离(2-color REMPI)光谱和质量分辨阈值电离(MATI)光谱,确定了2-乙氧基苯腈分子基态到第一电子激发态的激发能和精确的绝热电离能分别为(34 092±2)和(69 796±5) cm^-1。结合密度泛函理论计算和Franck-Condon光谱模拟对实验结果进行了分析并对振动谱带进行了归属。与苯腈相比,乙氧基取代使得光谱谱带变得丰富且复杂,许多乙氧基的振动模被观察到。这些实验和理论结果为相关的科学研究和应用开发提供重要参考资料。     

Sm原子的偶宇称高激发态的光谱研究

采用双色三步激发和光电离过程,对Sm原子的偶宇称高激发态的光谱进行了研究.先采用两条激发路线分别将Sm原子两步共振激发至待测的高激发态,然后利用光电离技术对其进行探测.分别将第一束激光的波长固定在627.50nm和624.41nm上,以便将Sm原子从亚稳态共振激发到由4f⁶6s6p电子组态所构成的两个原子状态上.第二束激光在440-700nm的波段范围内扫描,不仅使Sm原子在30040-38065cm^-1能域内的偶宇称高激发态上布居,将其进一步光电离,测量了其光谱.通过光谱定标和选择定则等分析手段,本工作不仅精确获得了136个态的能级位置,而且也唯一确定了其总角动量,并且给出了相关跃迁的相对谱线强度.     

铜原子的二步三光子共振电离

本文研究了适合于共振激光消融质谱的铜原子的二步三光子共振电离过程。在较严格的条件下求解了该过程的速率方程,并分析了在脉冲激光作用下共振电离信号的探讨效率,以及影响电离效率的光通量等各种因素。本文的计算方法具有普适性,而其理论结果对于共振激光消融的实验研究具有指导意义。     

机载激光3D探测成像系统的关键技术

介绍了机载激光3D探测成像系统的应用领域和国内外发展现状,概括了小型无人机载激光3D成像检测系统(JIGSAW)、机载激光测深系统(LADS)、直升机3D-LZ Imaging LADAR及机载对地高分辨详查系统的基本组成、技术指标以及各自的特点。阐述了激光3D成像系统的工作原理与扫描方式的分类,并重点对其单元核心技术即激光测距系统、激光光轴控制与指向测量系统、数据图像处理技术与显示系统进行了研究。最后,简单综述了机载激光3D探测成像系统的发展前景。     

机载激光3D探测成像系统的关键技术

介绍了机载激光3D探测成像系统的应用领域和国内外发展现状,概括了小型无人机载激光3D成像检测系统（JIGSAW）、机载激光测深系统（LADS）、直升机3D-LZ Imaging LADAR及机载对地高分辨详查系统的基本组成、技术指标以及各自的特点。阐述了激光3D成像系统的工作原理与扫描方式的分类,并重点对其单元核心技术即激光测距系统、激光光轴控制与指向测量系统、数据图像处理技术与显示系统进行了研究。最后,简单综述了机载激光3D探测成像系统的发展前景。     

半导体激光器光束质量改善新技术综述

半导体激光器是一种重要的光电器件,其出射光束的质量改善在应用中具有十分重要的意义。介绍了采用折射原理的渐变折射率透镜光束改善系统,以反射原理为依据的高精度反射元件,以衍射理论为基础的二元系统和多原理结合的光束性能改善系统。对近期国内外出现的像散梯度渐变折射率透镜、液胞器件、独立反射元件等新技术进行了阐述。     

New improved methods of X-ray detection

We present CCDs (CCD = charge-coupled device) as high performance X-ray detectors. These silicon pixel detectors (whose concept was invented in 1970) are mainly used today for detection of visible light with digital cameras. Generally, X-rays are detected by inserting a phosphorescent screen and collecting the light obtained onto the CCD. However X-rays can also be detected directly with excellent background rejection capabilities, good energy resolution and intrinsic pixel-size position resolution but with mediocre efficiency in a relatively small energy range and little or no timing information. For this application a slow, low noise electronics is needed. We will discuss how these detectors work, their advantages and disadvantages as well as future possibilities and limitations. This revised version was published online in August 2006 with corrections to the Cover Date.     

New approach of semiconductor laser related technologies for ultrafast photonics

Ultrashort laser pulses offer new jump in information and communication technology. Especially semiconductor laser based ultrafast photonic devices and systems are promising. We review our new approaches for femtosecond pulse generation, and thin film technology for broad band semiconductor optical amplifiers.     

Spectroscopic detection of biological NO with a quantum cascade laser

Two configurations of a continuous wave quantum cascade distributed feedback laser-based gas sensor for the detection of NO at a parts per billion (ppb) concentration level, typical of biomedical applications, have been investigated. The laser was operated at liquid nitrogen temperature near λ=5.2 μm. In the first configuration, a 100 m optical path length multi-pass cell was employed to enhance the NO absorption. In the second configuration, a technique based on cavity-enhanced spectroscopy (CES) was utilized, with an effective path length of 670 m. Both sensors enabled simultaneous analysis of NO and CO₂ concentrations in exhaled air. The minimum detectable NO concentration was found to be 3 ppb with a multi-pass cell and 16 ppb when using CES. The two techniques are compared, and potential future developments are discussed. Received: 1 November 2000 / Revised version: 19 January 2001 / Published online: 20 April 2001     

New particle detection methods at the Large Hadron Collider

Detection methods used at the Large Hadron Collider in the ATLAS, CMS, ALICE, and LHCb installations are briefly reviewed.     

Electron holography of biological samples

In this paper, we summarise the development of off-axis electron holography on biological samples starting in 1986 with the first results on ferritin from the group of Tonomura. In the middle of the 1990s strong interest was evoked, but then stagnation took place because the results obtained at that stage did not reach the contrast and the resolution achieved by conventional electron microscopy.

To date, there exist only a few (12) publications on electron holography of biological objects, thus this topic is quite small and concise. The reason for this could be that holography is mostly established in materials science by physicists. Therefore, applications for off-axis holography were powerfully pushed forward in the area of imaging, e.g. electric or magnetic micro- and nanofields. Unstained biological systems investigated by means of off-axis electron holography up to now are ferritin, tobacco mosaic virus, a bacterial flagellum, T5 bacteriophage virus, hexagonal packed intermediate layer of bacteria and the Semliki Forest virus. New results of the authors on collagen fibres and surface layer of bacteria, the so-called S-layer 2D crystal lattice are presented in this review. For the sake of completeness, we will shortly discuss in-line holography of biological samples and off-axis holography of materials related to biological systems, such as biomaterial composites or magnetotactic bacteria.     

Interaction of biological and nonbiological surfaces. New opportunities for research and technologies using synchrotron radiation

The applicability of synchrotron radiation to implementation of medical ideas associated with introduction of nonbiological objects into a human body—implants, drug nanocapsules, and X-ray therapeutic means (metal nanoparticles and nanocrystalline phosphors and scintillators)—is considered. Synchrotron radiation presents new possibilities of analyzing the surface with a resolution comparable to the sizes of biological nanostructures involved in interactions such as chemical and biochemical modification of implant surfaces in vitro; activation of implant surface integration with biological tissue in a tissue culture (in vitro) and in vivo; biochemical modification of therapeutic nanoparticle surface in vitro; immunocamouflage by host proteins; attachment of “molecular targets”, i.e., antibodies, to target tissue to provide targeted delivery vehicles; and local activation of X-ray therapeutic drugs and drug nanocapsules in biological tissues. A functional block diagram of a medical technological station is given.