Tribological properties of diamond-like carbon films deposited by pulsed laser arc deposition

A novel method, pulsed laser arc deposition combining the advantages of pulsed laser deposition and cathode vacuum arc techniques, was used to deposit the diamond-like carbon (DLC) nanofilms with different thicknesses. Spectroscopic ellipsometer, Auger electron spectroscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and multi-functional friction and wear tester were employed to investigate the physical and tribological properties of the deposited films. The results show that the deposited films are amorphous and the sp$^{2}$, sp$^{3}$ and C--O bonds at the top surface of the films are identified. The Raman peak intensity and surface roughness increase with increasing film thickness. Friction coefficients are about 0.1, 0.15, 0.18, when the film thicknesses are in the range of 17--21~nm, 30--57~nm, 67--123~nm, respectively. This is attributed to the united effects of substrate and surface roughness. The wear mechanism of DLC films is mainly abrasive wear when film thickness is in the range of 17--41~nm, while it transforms to abrasive and adhesive wear, when the film thickness lies between 72 and 123~nm.     

实时离子探测器——塑料闪烁体性能的实验研究

利用静电离子加速器对实时离子探测器——塑料闪烁体的特性 (包括灵敏度、动态范围、能量响应, 及空间分辨等)进行了实验研究,并对闪烁体探测器与其他传统的离子探测器的特性进行了比较. 对闪烁体在激光等离子体实验的离子束诊断中的可能应用进行了探讨.塑料闪烁体的应用可满足高重复频率激光等离子体离子加速实验高效率运行的要求,为实验研究提供强有力的支持.     

氮气在100 eV以下的绝对振子强度密度

在入射电子能量为2500 eV、能量分辨为100 meV的条件下，得到了氮气在100 eV以下的绝对光学振子强度密度和广义振子强度密度；得到了23 eV和31.4 eV两个超激发态的绝对广义振子强度、并讨论了它们的动量转移依赖特性。     

高温超导薄膜在微波双工器上的应用

本文采用全波电磁仿真方法设计、制作并测试了一种工作于C波段的星载高温超导微波双工器,采用的材料是在厚度为0.5mm介电常数为23.5的LaAlO3衬底上用磁控溅射法制备而成的双面氧化物高温超导薄膜YBCO.利用在微波范围内,高温超导薄膜的Q值比常规导体高1～3个数量级的特点,实现了器件的小型化和低插损.     

高温超导窄带广义切比雪夫函数滤波器

提出了一种用于高温超导滤波器制作的新结构窄带广义切比雪夫函数高、低通滤波器级联方式.该方式利用高温超导低插损特性,可以有效地降低极陡峭广义切比雪夫函数低通、高通滤波器的带边频滚降.依靠高、低通滤波器级联方式构建新形式的窄带极陡峭低插损高温超导滤波器,并与已有高温超导滤波器进行了比较分析.     

质子交换膜燃料电池低化学计量比的性能研究

以质子交换膜燃料电池实际应用为背景,研究了在反应物低化学计量比下,质子交换膜燃料电池不同温度、压力下的性能。得到了电池温度,压力对反应物化学计量比的影响。实验结果表明,反应物化学计量比1.0的电池性能低于足量反应气体工况下的电池性能;化学计量比为1.3时,电池能够在预期电流强度下稳定运行;反应气体的传质过程影响反应所需的化学计量比;当提升压力至0.13 MPa,化学计量比1.0的电池性能与足量反应气体工况下的性能相当。     

Reflecting a single attosecond pulse by using periodic Mo/Si multilayer mirrors with different layers

The reflecting of a single attosecond pulse from a periodic Mo/Si multilayer was investigated. By changing the number of bi-layers, the periodic multilayer showed greatly different spectral and temporal responses of the attosecond pulse reflection, which has been discussed in detail in this paper. The capability of attosecond pulse reflection of the periodic multilayers with different bi-layer numbers has been evaluated using suitable temporal parameters. In addition, the condition for obtaining high-efficiency reflected pulses has been analyzed by comparing the pulse responses of the periodic multilayer with different layers. The transfer-matrix method together with the fast Fourier transform has been used in our simulation.     

激光击穿光谱技术监测固土过程中阳离子交换

为了实时探测离子土固化剂(ISS)在固土过程中的阳离子交换量(CEC),采用激光击穿光谱技术(LIBS),对ISS处理后的土壤溶液中的K、Ca、Na、Mg、Al、Si这6种离子含量进行探测。分别对由不同配比(1∶100、1∶200和1∶300)的ISS处理过的高岭土、膨胀土、红粘土等5种标准土壤进行了研究,结果表明:同一土壤中的各种离子随ISS配比的变化趋势各不相同;不同土壤与ISS作用的效果各不相同;ISS的配比并非越高越好。这些工作为ISS固化机理的研究提供实验依据,而利用激光击穿光谱技术进行探测的方式为ISS固化机理的研究提供了新的思路。     

基于顶空及表面增强拉曼散射(SERS)结合的葱属植物挥发性物质研究

为了在常温下鉴定新鲜植物样品的挥发性物质,且避免繁杂前期样品的制备过程,将新鲜样品切细后置入顶空瓶中,用注射器抽取顶空瓶上方的挥发性物质注入用微波法制备的纳米银溶胶中,用R-3000便携式拉曼光谱仪进行SERS的测量。获得了葱属植物大蒜、韭菜、葱的挥发性物质的表面增强拉曼光谱(SERS)。大蒜的SERS谱中较强的峰出现在307,399,569,711,1 182,1 287,1 397,1 622 cm-1处。韭菜的SERS谱中最强的峰出现在672 cm-1,较弱的峰出现在274,412,575,1 185,1 289,1 396,1 618 cm-1处。葱的SERS谱中最强的峰出现在693 cm-1,次强峰出现在372,888,1 023 cm-1处,较弱的峰出现在1 088,1 211,1 322 cm-1。获得二烯丙基二硫(diallyl disulfide)、烯丙基甲基硫醚(allylmethyl sulfide)、1-丙硫醇(1-Propanethiol)的液态、气态的SERS谱。经对比研究得出：吸附在银表面的大蒜、韭菜、葱的主要挥发性物质分别是二烯丙基二硫(diallyl disulfide)、烯丙基甲基硫醚(allyl methyl sulfide)、1-丙硫醇(1-Propanethiol)。同是葱属植物但不同种大蒜、韭菜、葱其吸附在银表面的主要的挥发性物质不一样,吸附在银表面的各种葱的主要挥发性物质都是1-丙硫醇。该实验结果表明顶空与SERS结合,不需要复杂的提取过程,可直接用于新鲜植物的挥发性物质快速检测。     

Analysis of detection limit to time-resolved coherent anti-Stokes Raman scattering nanoscopy

In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit （DL） to time-resolved CARS （T-CARS） nanoscopy based on our proposed additional probe-beam-induced phonon depletion （APIPD） method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise （SNR） and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume （40-nm suppressed focal scale in APIPD method）, the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.