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本文报道锂蒸气中由双光子泵浦所产生的位于紫外、可见和红外区的相干和受激辐射。包括:由一特殊六波混频过程产生的在1.03μm附近的可调谐相干辐射,由锂分子双光子离解或原子串级跃迁产生的波长为812.6nm的受激辐射,以及由四波混频产生的位于323.3nm和670.8nm的相干辐射。
关键词: 相似文献
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钾原子中多种受激辐射参与的混频过程 总被引:2,自引:1,他引:1
当双原子共振激发钾原子于6S能级时,由光泵受激辐射和电离复合受激辐射参与的六波或四波混频,产生了位于紫外和紫区的诸多相干辐射、文中对多种混频机制进行了分析和讨论,并对所测得的相干辐射线进行了标识. 相似文献
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在Mg蒸汽中,将入射激光频率调谐到3s~(21)S—3s4s~1S双光子共振频率上,通过三次谐波的产生(THG),得到波长为1533(?)的真空紫外相干辐射,其光子产额大于5×10~9光子/脉冲。三种惰性气体:He、Ar和Kr分别作为缓冲气体。实验表明它们对于Mg蒸汽中三次谐波的产生都是有效的。文章讨论了限止真空紫外辐射产生的几个因素。 相似文献
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BFEL装置短电子束团相干同步辐射产生理论计算与实验设计 总被引:1,自引:0,他引:1
分析和数值计算了利用BFEL装置的30MeV射频直线加速器提供的4ps电子束团产生的宽带连续的强相干同步辐射.由讨论可知,该束团可直接用以产生毫米波段相干同步辐射;通过压缩束团宽度至1ps甚至亚ps,可获得宽带连续(覆盖远红外—毫米波段)的强相干辐射.由于这种辐射位于相干辐射的珍稀或空白区,因而具有极高的应用价值.在该波长范围内,相干辐射功率约为非相干辐射的108—109倍.依赖于所选的波长范围和接收角,辐射功率在几百微瓦至毫瓦量级.最后给出辐射产生和束团测量的实验构想. 相似文献
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用适当波长的激光混合激发原子-分子样品,和通过原子-分子碰撞能量转移,可产生从紫外到红外宽波段范围内的受激和相干辐射,其中包括固定波长辐射,可调谐辐射以及宽带辐射以及宽辐射。这是一个物理涵义极为丰富并具有应用前景的研究领域。 相似文献
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用适当波长的激光混合激发原子-分子样品,和通过原子-分子碰撞能量转移,可产生从紫外到红外宽波段范围内的受激和相干辐射,其中包括固定波长辐射、可调谐辐射以及宽带辐射。这是一个物理涵义极为丰富并具有应用前景的研究领域。 相似文献
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紫外辐射对牛血清白蛋白影响的拉曼光谱分析 总被引:4,自引:0,他引:4
检测了牛血清白蛋白粉末和水溶液及其经过40min、3h、5h和8h紫外辐射的拉曼光谱图。实验结果表明紫外辐射改变了牛血清白蛋白中硫硫键的几何构型,40min的紫外辐射使牛血清白蛋白粉末中一半以上的硫硫键由“扭式-扭式-扭式”构型变成了“反式-扭式-扭式”构型,经过3h和5h的紫外辐射,从拉曼谱图上已看不到表征硫硫键几何构型的谱峰。40min和3h的紫外辐射使牛血清白蛋白水溶液中部分硫硫键由“扭式-扭式-扭式”构型变成了“反式-扭式-扭式”构型,但当紫外辐射时间长达5h时,硫硫键又只有“扭式-扭式-扭式”一种构型。经过紫外辐射,牛血清白蛋白粉末中酪氨酸残基有由“暴露”式向“埋藏”式转变的趋势;水溶液中一部分酪氨酸残基经紫外辐射后由“暴露”式变成了“埋藏”式。紫外辐射对粉末状态牛血清白蛋白主链构象影响要比溶液状态大。 相似文献
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We herein report a novel method of employing 254 nm of UV radiation (UV) for the modification of a polyethyleneimine (PEI) layer on silicone oxide film. In this study, a PEI layer composed of a 50 mM sodium carbonate solution (pH 8.2) was formed on the surface of a silicone oxide film with spontaneous adsorption. Then, thin film of PEI was patterned by UV radiation. To determine the effect of the UV radiation, fluorescence microscopy, X-ray electron spectroscopy (XPS), and Fourier Transform Infrared spectroscopy (FT-IR) analyses were performed. These results indicated that UV radiation could cause changes in the surface characteristics of the PEI layer. Subsequently, FT-IR analysis showed changes in the chemical composition of the PEI exposed to UV radiation, such as the disappearance of the amine. Based on these results, we can conclude that UV radiation could be used to eliminate the amine group selectively and that this technique could be applied to create a pattern on the surface of a PEI layer. 相似文献
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《Radiation measurements》2000,32(3):193-200
The increase in environmental solar UV radiation due to depletion of ozone layer is a recent challenge to human health (skin cancer and eye effects) in countries having clear skies. Therefore, applying integrated, passive and inexpensive techniques to assess solar UV radiation is very much essential. Measurements of environmental solar UV radiation in Dhahran, Saudi Arabia area were carried out for a period of two months in the summer period in 1996 using two techniques in parallel namely: passive nuclear track detectors and active solar UV radiometers. Some of the nuclear track detectors were mounted in different conditions such as: under shadow band, on solar tracking mechanism following the solar rays. Others were mounted on perpendicular, tilted and horizontal surfaces in sunlight. All detectors were attached to a wooden background of the same thickness (0.5 cm) to eliminate interference of the heat effect of various support materials and have uniformity of the support materials. The assessment was carried out for different periods extending from two to nine weeks continuously. The investigated period covered the hottest months in Saudi Arabia (July and August) when the sky was clear of clouds. The results indicate linear correlation between alpha track diameters and the integrated exposure to solar UV as measured by the solar UV radiometer for all nuclear track detector positions and orientations. The highest slope has been observed for the detectors placed on solar tracking mechanism following the solar rays and the lowest from detectors oriented under the shadow band on horizontal position (measuring the diffused UV radiation only). The results show that most of the measured UV radiation (60%) were from the diffused UV radiation. The characteristics of the upper layer of the detectors are changed after chemical etching very quickly, with increase in the exposure time to UV solar radiation at certain orientation. The results encourage the use of nuclear track detectors for environmental and personal solar UV dosimetry on a large scale in Saudi Arabia and similar hot and clear-sky countries. 相似文献
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E. K. Kozlova V. A. Sergunova E. A. Krasavin A. V. Boreyko A. V. Zavialova A. P. Kozlov A. M. Chernysh 《Physics of Particles and Nuclei Letters》2016,13(1):140-148
The purpose of the study is to investigate local topological defects in the erythrocyte membranes resulting from the ultraviolet (UV) radiation of blood in vitro. Biological effects in the erythrocytes after exposure to UV radiation at a wavelength of 254 nm are equivalent to those after γ radiation. It has been shown that oxidative processes developing in a suspension upon UV radiation result in the disruption of the nanostructure of the membranes of erythrocytes. In the experiments, typical topological defects in the membrane nanostructure were observed. The parameters of the defects differed from the characteristics of the nanostructure of the control cell membrane without irradiation. The characteristic dimensions of the topological defects are commensurate with the size of the spectrin matrix. As a result of the exposure to the UV radiation, polymorphism of the erythrocytes was observed. 相似文献
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The light-enhanced NO<sub>2</sub> sensing properties of porous silicon gas sensors at room temperature 下载免费PDF全文
The NO2 gas sensing behavior of porous silicon(PS) is studied at room temperature with and without ultraviolet(UV) light radiation.The PS layer is fabricated by electrochemical etching in an HF-based solution on a p +-type silicon substrate.Then,Pt electrodes are deposited on the surface of the PS to obtain the PS gas sensor.The NO2 sensing properties of the PS with different porosities are investigated under UV light radiation at room temperature.The measurement results show that the PS gas sensor has a much higher response sensitivity and faster response-recovery characteristics than NO2 under the illumination.The sensitivity of the PS sample with the largest porosity to 1 ppm NO2 is 9.9 with UV light radiation,while it is 2.4 without UV light radiation.We find that the ability to absorb UV light is enhanced with the increase in porosity.The PS sample with the highest porosity has a larger change than the other samples.Therefore,the effect of UV radiation on the NO2 sensing properties of PS is closely related to the porosity. 相似文献
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A source of spontaneous UV radiation (excilamp) with a maximum radiation intensity at a wavelength of 308 nm is created. The
active medium of the excilamp consists of a mixture of Xe with a CsCl vapor, and this mixture is excited in a longitudinal
pulsed-periodic discharge. The B → X transition in the XeCl* exciplex molecule most strongly contributes to the total UV radiation power of the excilamp. The
spectral composition of the UV radiation, the time characteristics of the source, and the formation of exciplex molecules
as a function of the main discharge excitation parameters are studied. 相似文献
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We have generated 4.7 W of UV (255-nm) radiation with wall plug efficiency of 0.12% by frequency doubling the green (511-nm) output of a kinetically enhanced medium-scale copper-vapor laser (CVL) in cesium lithium borate (CLBO). Frequency doubling in beta -barium borate produced 3.9 W of UV radiation with wall plug efficiency of 0.1%. We found that conversion was better with CLBO because of the reduced constraints on CVL beam quality, less UV absorption, and smaller UV walk-off. 相似文献
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The light-enhanced NO2 sensing properties of porous silicon gas sensors at room temperature 下载免费PDF全文
The NO2 gas sensing behavior of porous silicon(PS) is studied at room temperature with and without ultraviolet(UV) light radiation.The PS layer is fabricated by electrochemical etching in an HF-based solution on a p +-type silicon substrate.Then,Pt electrodes are deposited on the surface of the PS to obtain the PS gas sensor.The NO2 sensing properties of the PS with different porosities are investigated under UV light radiation at room temperature.The measurement results show that the PS gas sensor has a much higher response sensitivity and faster response-recovery characteristics than NO2 under the illumination.The sensitivity of the PS sample with the largest porosity to 1 ppm NO2 is 9.9 with UV light radiation,while it is 2.4 without UV light radiation.We find that the ability to absorb UV light is enhanced with the increase in porosity.The PS sample with the highest porosity has a larger change than the other samples.Therefore,the effect of UV radiation on the NO2 sensing properties of PS is closely related to the porosity. 相似文献
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针对辐射增益是紫外像增强器的主要性能参数,决定着紫外像增强器的综合性能,提出一种用于测试紫外像增强器辐射增益的测试仪,测试波长范围为200 nm~400 nm,亮度测量视场角可选(1/8)、(1/4)、(1/2)、1、2、3。通过改变微通道板电压、阴极电压和荧光屏电压等参数,完成对紫外像增强器的辐射增益测试,测试结果表明:测试曲线变化趋势和紫外像增强器的工作特性相吻合,入射紫外辐射强度调节范围为10-11W/cm2~10-7W/cm2,辐射计最低探测强度可达10-11W/cm2,最低亮度探测阈值可达310-4cd/m2,辐射增益测试重复性优于8%。 相似文献