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1.
一种新型准分子激光器循环系统中的密封传动技术,具有可耐高气压,不失耦,不使用昂贵强磁材料,结构简单等优点,虽有涡流损失过大之不足,但能很好地适用于小功率下运行。  相似文献   
2.
脉冲激光沉积SrBi2Ta2O9铁电薄膜电容特性研究   总被引:2,自引:0,他引:2  
用PLD方法成功地制备了SBT铁电薄膜,并制作成Pt/SBT/Pt薄膜电容器。SBT薄膜的晶面取向以(008)和(115)为主。在5V电压下,极化反转,并且得到较饱和的电滞回线,剩余极化强度和矫顽电场分别为84μC/cm2和57kv/cm。IV特性测试显示两个对称的双稳峰,并得到零电压下,面积为314×104μm2,厚度为035μm的电容器,电容约为560pF,介电常数约为600。疲劳测试表明Pt/SBT/Pt具有优良的抗疲劳特性。  相似文献   
3.
准分子激光的应用   总被引:2,自引:0,他引:2  
本文介绍了准分子激光器的基本类型、主要应用领域及其与材料相互作用的机理。对准分子激光在电子工业、生物医学和材料加工方面的一些重要应用做了比较详细的论述。  相似文献   
4.
多种原子团及其离子已具有在VUV/XUV波段产生受激发射的能力。本文介绍了产生短波长相干辐射的方法、研究现状、研究方法和原子团的结构与受激发射。  相似文献   
5.
We have grown thin carbon films by pulsed laser deposition and have investigated the extent to which the properties of such films, as well as the processes responsible for these properties, are laser wavelength dependent. Films were grown by ablating material from a graphite target onto room temperature Si(100) substrates with 1064 and 248 nm laser radiation. The films were analyzed byin situ electron energy loss spectroscopy and byex situ Raman spectroscopy. The results indicated that films grown with 1064 nm ablation were graphitic, while those grown with 248 nm radiation were diamond-like. We have also examined the mass and kinetic energy distributions of the particles ejected from graphite by the two laser wavelengths. The results indicated that irradiation of graphite with 1064 nm laser radiation results in the ejection of a series of carbon cluster ions C n + (1 ≤ n ≤ 30) with mean kinetic energies less than 5 eV. Ablation of graphite with 248 nm radiation results in the ejection of primarily C 2 + and C 3 + with mean kinetic energies of 60 and 18 eV, respectively. These results suggest that large, low energy clusters produce graphitic films, while small, high energy clusters produce films of diamond-like carbon.  相似文献   
6.
新生猪胰岛样细胞团经准分子激光照射预处理后,其免疫原性明显降低,表明经激光预处理,有可能延长移植物存活时间。  相似文献   
7.
In this work a treatment for surface preparation to improve mechanical resistance in adhesive bonding of plastic composites reinforced with fibres and metallic material, has been performed using an excimer laser. The following couplings have been selected to reproduce joints commonly used in the aerospace and automotive industry: CFC (carbon fibre composite) with CFC, CFC with Al 2024T3, Al 99% with Al 99%, GFC (glass fibre composite) with zinc-coated sheet in low carbon steel FeP01. The surfaces have been prepared using an excimer laser, adopting several values of laser parameters. The obtained surfaces have been examined by optical and scanning electron microscope: comparative measures of wetting and roughness have been performed to obtain an accurate characterisation and to select the proper finishes suitable to improve the mechanical resistance of the joints. The results obtained show that laser treatment always improves the final resistance of the joint; notable increases, and no significant surface damages have been highlighted. Better results have been obtained with the Al 99% with Al 99% joints which, with a low number of pulses treatment, have shown an increase of mechanical resistance up to the 70%.  相似文献   
8.
By UV-laser-irradiation a controllable change of the refractive index of some polymers can be attained in the irradiated zone. The detailed UV-photon-induced process mechanisms have been investigated on the basis of PMMA employed as an UV-modifiable model polymer. By mask lithographic methods the UV-laser-assisted technology for the modification of the polymer optical properties enables the local increase of the refractive index and thus the fabrication of integrated-optical waveguiding elements in the surface of a planar polymer chip. These elements are relevant for the manufacturing of complex integrated-optical components. The optical and functional properties of the integrated-optical waveguides have been characterized.  相似文献   
9.
An excimer laser may be used for preadhesion treatment of aluminum alloys. This method presents an alternative to the use of ecologically unfriendly chemicals involved in conventional anodizing pretreatments.

Experimental results indicate that preadhesion laser surface treatment significantly improved the shear strength of modified-epoxy bonded aluminum specimens compared with untreated and anodized substrates. The best results were obtained with laser energy of about 0.2 J/Pulse/cm2 where single lap shear strength was improved by 600-700% compared with that of untreated Al alloy, and by 40% compared with chromic acid anodizing pretreatment.

The mode of failure changed from adhesive to cohesive as the number of laser pulses increased during treatment. The latter phenomenon has been correlated with morphology changes as revealed by electron microscopy, and chemical modification as indicated by Auger and infrared spectroscopy.

It can be concluded that the excimer laser has potential as a precise, clean and simple preadhesion treatment of Al alloys.  相似文献   
10.
The absorption, fluorescence excitation and emission spectroscopy, and time‐dependent spectrofluorimetry have been used to study the photophysics of copolymers of N‐vinylcarbazole with different monomers like vinyl acetate, methyl acrylate, methyl methacrylate, butyl acrylate, and butyl methacrylate in dichloromethane. In all the copolymers and at different N‐vinylcarbazole content, the absorption spectra reflect only the monomer carbazole units. The two kinds of excited monomer species of N‐vinylcarbazole are present in S1 state. Short‐lived (~3 ns) excited monomer decays forming low energy excimer obtained by the complete overlap of the excited carbazole monomer. The long‐lived excited monomer (~8 ns) decays to ground state without formation of any excimer. The high energy excimer is relatively short‐lived and is formed by the partial overlap of the carbazole units. The presence of bulky group in the copolymer chain hinders the formation of excimers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 372–380, 2006  相似文献   
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