Temporally resolved laser induced plasma diagnostics of single crystal silicon — Effects of ambient pressure

Laser-Induced Breakdown Spectroscopy of silicon was performed using a nanosecond pulsed frequency doubled Nd:YAG (532 nm) laser. The temporal evolution of the laser ablation plumes in air at atmospheric pressure and at an ambient pressure of ∼ 10^− 5 mbar is presented. Electron densities were determined from the Stark broadening of the Si (I) 288.16 nm emission line. Electron densities in the range of 6.91 × 10¹⁷ to 1.29 × 10¹⁹ cm^− 3 at atmospheric pressure and 1.68 × 10¹⁷ to 3.02 × 10¹⁹ cm^− 3 under vacuum were observed. Electron excitation temperatures were obtained from the line to continuum ratios and yielded temperatures in the range 7600–18,200 K at atmospheric pressure, and 8020–18,200 K under vacuum. The plasma morphology is also characterized with respect to time in both pressure regimes.     

圆锥形血管中的振荡发展流动

本文在小锥度角的假设下,研究了圆锥形血管的非定常振荡的发展流动问题.导得了相应的速度分布公式.分析表明,所有收缩的圆锥形血管的流动都是发展流动,而且锥度角对发展流动的影响随着锥度角的增大而增大.     

GLOBAL STABILITY OF SOLUTIONS WITH DISCONTINUOUS INITIAL DATA CONTAINING VACUUM STATES FOR THE RELATIVISTIC EULER EQUATIONS

The global stability of Lipschitz continuous solutions with discontinuous initial data for the relativistic Euler equations is established in a broad class of entropy solutions in L∞containing vacuum states. As a corollary, the uniqueness of Lipschitz solutions with discontinuous initial data is obtained in the broad class of entropy solutions in     

CO2／CH4重整镍基催化剂制备与性能的关系

一般浸渍法与真空浸渍法的比较说明,真空浸渍制备的催化剂,其表面具有较多的Ｎｉ原子,催化活性较高,现场ＴＰＯ实验表明,ＣＯ岐化的积炭量大于ＣＨ４解离的积炭量。从而提出镍基催化剂的积炭主要来自反应生成气ＣＯ的岐化。     

环氧乙烷的真空紫外同步辐射光电离与光解离

利用真空紫外同步辐射和自制的飞行时间质谱（TOF－MS）仪,研究了环氧乙烷的光电离与光解离过程,通过测量各离子的光电高效率（PIE）曲线,获得了该分子的电离势和所有碎片离子的出现势．分析了离子的光电离解离通道,并讨论了它们的竞争情况．结合有关公认的热力学数据,算出它们的标准生成焓．     

V2O5电致变色薄膜的Raman光谱

近年来,通过向过渡金属氧化物薄膜注入Ｌｉ 制作可调节光透过率的电变色器件已越来越引起广泛的重视[1、2].由于Ｖ2Ｏ5薄膜的稳定性差,限制了它在实际中的应用.因此,为了获得变色效率高、稳定性和可逆性能好的Ｖ2Ｏ5薄膜,使用了多种制备方法,如磁控溅射法[3、6]、电化学沉积法[7、8]、溶胶凝胶法[9、10]、旋涂法[11、12]、真空蒸镀法[13、14]等.但是,无论那种方法都要解决Ｖ2Ｏ5本身在Ｈ2Ｏ或醇等的电解质溶液中电致变色时的溶解问题,通常采用控制薄膜的沉积温度或者退火处理来提高薄膜的电致变色性能[3、4、11].为了探明薄膜结构与电致变色…     

Energy transfer studies in krypton-xenon mixtures excited in a cooled DC discharge

The VUV spectrum of gaseous mixtures of krypton with a small amount of xenon added was investigated in the range 115-200 nm. The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using liquid nitrogen. The mixed molecule band around the XeI resonance line at nm and the mixed molecule continuum to the long wavelength side from the line were analysed. The band around nm was identified as transitions between a weakly bound excited state and the weakly bound ground state of XeKr molecules. When cooling the capillary wall, the appearance of the Xe₂ continuum was observed. The effect is ascribed to energy transfer between molecular states as a consequence of radiation trapping in the band around nm. The role of the mixed molecule in the formation of the VUV spectrum of the gas mixture is discussed and underlined. Received 12 May 1999 and Received in final form 27 August 1999     

Identification of structures in absorption spectrum of Kr-Xe gas mixtures close to the Xe resonance line at 146.96 nm

The origins of spectral structures that appear close to the Xe resonance line at 146.96 nm in absorption spectra of Kr gas with an admixture of Xe are discussed in this paper. It is shown that these structures can result from bound-bound and bound-free transitions in the Xe-Kr molecule between the ground state and the 1(³P₁) excited state, which both are weakly-bound. The depth of the excited state is estimated. An introduction of a hump on the 1(³P₁) state internuclear potential is suggested. Received 15 December 1999 and Received in final form 20 February 2000     

有机分子束外延技术与研究进展

本介绍了超高真空分子束外延生长有机薄膜的技术及基研究进展,讨论了外延材料的纯化过程和杂质对外延薄膜的影响;从理论和实验观点评论了薄膜的生长性质和膜的有序结构。超高真空有机分子束外延技术是一种多用途的高技术,可以生长有机、无机、有机／无机混和的薄膜结构。这种薄膜结构是示来光学和电子器件有希望应用的新一类工程材料。