排序方式: 共有91条查询结果,搜索用时 31 毫秒
51.
为了提高脉冲激光制备薄膜的质量,准确掌握电声弛豫时间是关键,它对脉冲激光脉宽和能量密度的选取起着决定性的作用. 文中以铝靶材为例,利用经典的双温方程通过时域有限差分法(FDTD)得到电子、离子亚系统的温度随时间和位置演化的图像,进而得到电声弛豫时间的准确值. 这样便能准确划分热烧蚀和非平衡烧蚀,从而更好地控制激光的烧蚀过程. 同时找出了电声弛豫时间随激光脉宽以及能量密度变化的规律.
关键词:
飞秒激光
电声弛豫时间
双温方程
激光能量密度 相似文献
52.
Quantum Degenerate Fermi--Bose Mixtures of 40K and 87Rb Atoms in a Quadrupole-Ioffe Configuration Trap 总被引:2,自引:0,他引:2 下载免费PDF全文
We report on the attainment of quantum degeneracy of 40^K by means of efficient thermal collisions with the evaporatively cooled 87^Rb atoms. In a quadrupole-Ioffe configuration trap, potassium atoms axe cooled to 0.5 times the Fermi temperature. We obtain up to 7.59 × 10^5 degenerate fermions 40^K. 相似文献
53.
The iridium-catalyzed asymmetric hydrogenation of β-keto esters with chiral tridentate P,N,N-ligands (f-amphox) has been developed. Under the optimized conditions, a wide range of β-keto esters can be hydrogenated smoothly, affording the corresponding β-hydroxy esters in good to excellent enantioselectivities (up to 95% ee). 相似文献
54.
XU De-Zhi 《中国物理C(英文版)》1983,7(1):13-19
In this paper we propose an SU(4)×SU(2)×U(1) unified model, in which the stratons and leptons of every generation belong to the same Multiplet, and the leptons will couple to the stratons. But this kind of coupling cannot cause the proton decay, and has only some effects in high energy scatterings. This model predicts the existense of two neutral intermediate bosons, instead of one, and the value of Weinberg angle to be sin2θw=0.25. The neutrinos have reasonable masses in the model. 相似文献
55.
ZHANG Duan-Ming FANG Ran-Ran LI Zhi-Hua GUAN Li LI Li TAN Xin-Yu LIU Dan LIU Gao-Bin HU De-Zhi 《理论物理通讯》2007,48(1):163-168
We develop a new synthetical model of high-power pulsed laser ablation, which considers the dynamic absorptance, vaporization, and plasma shielding. And the corresponding heat conduction equations with the initial and boundary conditions are given. The numerical
solutions are obtained under the reasonable technical parameter
conditions by taking
YBa2Cu3O7 target for example. The
space-dependence and time-dependence of temperature in target at a certain
laser fluence are presented, then, the transmitted intensity through plasma
plume, space-dependence of temperature and ablation rate for different laser fluences are significantly analyzed. As a result, the satisfactorily good agreement between our numerical results and experimental results indicates that the influences of the dynamic
absorptance, vaporization, and plasma shielding cannot be neglected. Taking all the three mechanisms above simultaneously into account for the first time, we cause the present model to be more practical. 相似文献
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57.
钨酸锌纳米结构的水热合成及其光催化性能研究 总被引:1,自引:1,他引:0
使用柠檬酸钠辅助的水热法合成了具有不同形貌的ZnWO4(如片状、花状)纳米颗粒,并采用X-射线粉末衍射(XRD)、场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)等方法对样品的结构和组成进行表征。研究了溶剂组分和溶液pH值对产物形貌的影响。通过对反应产物形貌随时间变化的观察,提出了片状和花状ZnWO4纳米颗粒可能的生长机理。以罗丹明B(RhB)为催化降解对象,对样品在水溶液中的光催化性质进行了研究。结果表明,ZnWO4纳米颗粒的比表面积和孔径尺寸等结构特性对其光催化活性具有明显影响。 相似文献
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59.
对40K-87Rb原子冷却的半导体激光系统提出了一种实验方案,并进行了初步实验.采用三台外腔光栅反馈半导体激光器(ECDL)、四台注入锁定从激光器和一台半导体激光放大器组成激光系统.三台ECDL通过声光调制器产生四束光,分别作为40K和87Rb原子的冷却光和再抽运光,四束不同频率成分的激光分别注入锁定四台从激光器,然后Rb冷却光、K冷却光和K再抽运光再同时注入半导体激光放大器进行放大.该装置可同时产生冷却40K和87Rb原子的冷却光和再抽运光,结构紧凑、工作稳定. 相似文献
60.
De-Zhi Kong Zhi-Fang Yuan Xiao-Wei Zhang Xiao-Na Sheng Na Wang Song-song Xing Yu-Min Du Lan-Tong Zhang 《Chromatographia》2009,70(11-12):1743-1748
A rapid and simple method has been developed and validated for the determination of m-nisoldipine and its five related substances using micellar electrokinetic capillary chromatography (MEKC). The key factors, including pH, buffer concentration and buffer additive, sodium dodecyl sulfate (SDS) concentration, applied voltage and temperature were systematically investigated in an uncoated fused silica capillary. The total analysis time was less than 9 min. The forced degradation products of m-nisoldipine, which were induced by hydrogen peroxide, acidic and basic conditions, heat and light, were also tested. 相似文献