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1.
描述了用DMP-450型镀膜机改造,设计成应用于激光铀同位素分离的分离器装置。选用6000W电子枪作为加热泊,产生激光同位素分离实验所需的铀蒸气,对激光与铀原子相互作用区中的铀原子密度进行了估算。讨论了在蒸发中,由多普勒效应引起的谱线加宽衣热离子等对分离实验的影响因素和排除方法。还对高温下液态铀的强腐蚀性,加热坩埚和屏蔽罩的实验选择等方面进行了有益的探讨。  相似文献   

2.
水中放射性核素铀钍经浓缩,酸溶分解,制成酸性混合溶液,用TBP萃淋树脂萃取分离干扰元素并富集微量铀、钍,采用盐酸和蒸馏水分别洗脱钍、铀。在盐酸介质中,用偶氮胂Ⅲ显色,于波长660nm处测定钍络合物的吸光度;在pH=8时,5-Br—PADAP—OP溶液显色,于波长580nm处测定铀络合物的吸光度。检出限分别为铀0.10μg/L,钍0.05μg/L。随着科学的发展,具有放射性的元素铀、钍污染环境,损坏人类健康,因此,在环境监测中,微量铀、钍的测定是一个值得注意的问题,目前对于铀、钍的测定主要有分光光度法,荧光法,原子发射光谱法等。但这些方法,有的灵敏度低,有的选择性差,有的操作繁琐,因此不适宜于快速测定。本法研究了该方法具有灵敏度高、选择性好、操作简单快速、对环境污染小等优点。该方法用于水样中微量铀、钍的测定,结果满意。  相似文献   

3.
自从激光问世以来,以其高光亮度、单色性、定向性和超短脉冲性使人们在用激光进行同位素分离、浓缩铀等方面取得了长足的进步,利用超短脉冲激光进行反应动力学研究已开始起步,但是,鉴于能量因分子碰撞而损失,许多研究都是在低气压条件下进行的,以单体直接进行激光液相聚合的例子不多,目前还未见以激光进行阴离子型的聚合反应。我们利用激光能定向离解某一键的特点,以连续输出单模运转的CO_2激光,在未聚焦的情况下,对甲  相似文献   

4.
原子喷泉的发展得益于激光冷却原子技术。20世纪70年代中期,国际上就提出了激光冷却原子的设想。到了1989年.Stanford的S.Chudx组首先在实验中实现了Na的原子喷泉。由于冷原子喷泉预期的准确度要好于1×10^-16,使得大量的科研人员将目光投向原子喷泉,将这种全新的方式融入不同的研究领域(如重力测量、时间频率等)。  相似文献   

5.
在铬原子光刻中可采用铬原子束激光感生荧光(LIF)来实现激光频率的稳定,以满足原子光刻对激光频率稳定性的要求。激光感生荧光稳频技术除有很高的稳频精度以外,还可以获得相对于原子共振频率的一定失谐量。本文根据已有的实验条件和参数从铬原子束的速率分布、激光频率与荧光斑点中心横向位移的关系、二象限光电探测器测得的误差信号等方面对铬原子束激光感生荧光(LIF)稳频技术作了理论分析。  相似文献   

6.
自六十年代初第一台激光器问世以来,随着各类激光器的研制与发展,激光化学的基础与应用研究正在向实用化纵深发展。近十多年来,国内外大量探索研究表明:激光化学最有效地应用于:制备特种超微粒粉末材料(UFP—Ultrafine particles)、新型材料及高效催化荆、新型半导体材料及超导材料、新型结构材料及功能材料,分离各种同位素及超高纯物质,引发或加速各类化学反应,检测和诊断各类特定分子、原子、基团及化学键,研究化学动力学、动态学等领域。总之,激光化学的发展,无论在应用上和理论上都具有深远前景。  相似文献   

7.
针对某矿区含碳硅岩和碳质灰岩样品的铀分析应用标准方法分析过程复杂、分析结果不够准确的状况,采用激光荧光法,实验一种快速准确的分析方法。通过马弗炉灼烧和硝酸-氢氟酸-高氯酸冷浸湿法预处理,在一定的硝酸介质中铀酰离子与荧光增强剂生成稳定络合物,在激光激发下产生荧光。使用MUA型微量铀分析仪可直接用标准加入法测定样品中铀的含量。探讨了样品分解、酸度、灵敏度对不同铀含量样品的测定条件的影响。初步形成一种广含量的铀的可靠分析方法,从而提高了分析效率和准确度,并降低了分析成本。  相似文献   

8.
随着市场对稳定同位素需求的日益增加,要求对各种元素的同位素的检测结果要可靠,精度高,专用于铀化物的质谱仪进行了改装,调试,以适应于其他单一元素同位素及不同元素混合物的同位素的检测,本以Xe,SF6二种混合物的同位素为实例,采用改进了的质谱检测并对其结果给予评估,发现数据误差2%左右,有待进一步探索解决。  相似文献   

9.
铀薄膜有助于原子参数的测试研究,目前对铀薄膜研究的报道较少.利用超高真空磁控溅射法在单晶Si片上制备了铀薄膜.通过扫描电子显微镜(SEM)对铀薄膜的表面形貌进行了观察,利用X射线光电子能谱仪(XPS)及X射线衍射仪(XRD)对铀薄膜的表面结构及元素状态进行了分析和表征.结果表明:铀薄膜呈片状式生长,比较致密、连续,表面由铀及氧化铀组成,之下为纯铀.  相似文献   

10.
对来我国在高温气冷堆铀、钍燃料后处理技术方面取得的进展进行了评述。较详细地报导了我国在石墨燃料球固定床连续燃烧、ThO2燃料芯核加压溶解、分离钍、铀的单循环TBP溶剂萃取流程以及在50mm脉冲筛板柱上实现工艺条件下的流体力学及传质实验等关键技术上取得的突破。  相似文献   

11.
Abstract

We discuss effects of optical depth, beam focusing and non-perturbative atomic response on the spectrum of optical harmonics generated by an intense beam of laser radiation (up to 1014W cm?2) in a small volume of atomic vapour. We find remarkable enhancement of high harmonics at intensities beyond the perturbative limit.  相似文献   

12.
We study both theoretically and experimentally three-photon electromagnetically induced transparency and electromagnetically induced absorption resonances in inhomogeneously broadened 85 Rb atomic vapour driven by probe and drive laser radiations. We observe narrow Doppler-free absorption as well as transmission resonances for the probe field when the driving laser field is redshifted from the D1 or D2 lines of 85Rb; the frequency difference between the drive and probe fields is equal to the hyperfine splitting of the ground state of the atoms, and the probe field is tuned to the centre of the Doppler broadened atomic transition. We theoretically study the spectroscopic effect in both homogeneously and inhomogeneously broadened media. Our numerical simulations are in good agreement with the experimental results.  相似文献   

13.
14.
We theoretically investigate dressed-four-wave mixing (dressed-FWM) spectroscopy of rubidium atoms in a micrometric thin vapour. It is found that Dike-narrowing type Autler–Townes (AT) spectroscopy with high resolution can be achieved in a reverse Y-type four-level atomic system due to the phase-conjugated configuration of laser beams and the transient effects of atom–wall collision in the thin vapour. We also show that controllable suppression and enhancement of the dressed-FWM signal due to the evolution of atomic coherence can be obtained by selecting different coupling field intensities at the proper detuning of the probe and the coupling fields. This control of FWM processes can be interpreted by dressed state analysis and probably used in the design of optical switch and the enhancement of FWM processes for frequency conversion.  相似文献   

15.
Shen XK  Lu YF 《Applied optics》2008,47(11):1810-1815
Detection of uranium in solids by using laser-induced breakdown spectroscopy has been investigated in combination with laser-induced fluorescence. An optical parametric oscillator wavelength-tunable laser was used to resonantly excite the uranium atoms and ions within the plasma plumes generated by a Q-switched Nd:YAG laser. Both atomic and ionic lines can be selected to detect their fluorescence lines. A uranium concentration of 462 ppm in a glass sample can be detected by using this technique at an excitation wavelength of 385.96 nm for resonant excitation of U II and a fluorescence line wavelength of 409.0 nm from U II.  相似文献   

16.
K.B. Thakur  G.K. Sahu 《Vacuum》2004,75(3):283-292
We present results on the spatial distribution of copper vapour flux in the three-dimensional flow behaviour region under identical experimental conditions as a function of the temperature of a two-dimensional (2D) evaporating source. These experimental results clearly show that, with increasing source temperature, atomic collision processes along the length and the width of a 2D source differ, which results in a differential collimation of atomic beam which can be evaluated using different beam exponents in these directions. A generalized function describing the spatial distribution of atomic vapour from a point as well as from a 2D source and deviation from Knudsen's cosine law is presented. With this distribution function, the experimentally measured vapour flux distribution from a 2D source as a function of temperature, described in terms of Knudsen numbers ranging from 1.2 to 0.23, could be fitted to an accuracy of ±5%.  相似文献   

17.
A new experimental approach for growth rate determination of microdimensional aluminium stripes written by laser-induced chemical vapour deposition (LCVD) was developed. The aluminium lines were obtained by pyrolysis of trimethylaluminium (TMA) on (100) silicon monocrystalline wafer using the focused beam of a copper bromide vapour laser. Quantitative determination of the deposit was performed by its chemical removal from the substrate into a solution and further analysis performed using inductively coupled plasma atomic emission spectroscopy. Using this analytical method, dependences of the aluminium quantity on the partial pressure of TMA and the laser power were obtained. The growth rate at direct writing with a pulsed visible laser was calculated on the basis of aluminium quantity determinations. It is demonstrated that the proposed experimental approach could be successfully used for kinetic studies of LCVD processes.  相似文献   

18.
Reabsorption of spontaneously emitted photons, or radiation trapping, is a process that occurs when light interacts with optically thick media. It is shown, both theoretically and experimentally, that this effect in optically thick atomic vapour leads to a decrease in transmission of coherent laser radiation propagating under conditions of electromagnetically induced transparency (EIT). A simple theory is developed taking into account the radiation trapping, which is in a good agreement with the experimental observations and exact numerical simulation. This allows better understanding of the physics of EIT in general, and properties of dense coherent atomic media in particular.  相似文献   

19.
Alumina coatings find wide applications as tribological coatings and as corrosion protective coatings for structural materials against chemical attack. We have investigated alumina coatings deposited on Stainless Steel (SS) substrates via pulsed laser deposition (PLD) technique. Characterization tests performed on these coatings including their compatibility with liquid uranium suggests alumina to be a potential candidate as a coating material for handling and containment of liquid uranium. We present here results of our detailed parametric study including dependence of average mass removal rate on laser fluence and ablation geometry and average deposition efficiency during PLD. These measurements provide vital inputs facilitating proper choice of process parameters for PLD runs. Deposited coatings have been characterized in terms of their microstructure, surface profile, adhesion to substrate, crystalline phase and corrosion resistance against liquid uranium. Our PLD based alumina coatings have shown a high degree of compaction and excellent corrosion resistance to molten uranium even upto a temperature of 1165 °C.  相似文献   

20.
A new type of laser chemical vapour deposition process, in which the reactants are incorporated in the mist of the solvent, is proposed. It is applicable to prepare high-quality thin films from reactants having a low vapour pressure. By using a continuous wave CO2 laser, ZnS thin films, consisting of c-axis oriented ultrafine microcrystallites, have been prepared.  相似文献   

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