13CH4分子v3振动带空气和氮气加宽系数温度依赖性研究

采用中红外波段连续可调谐二极管激光器和自行研制的低温吸收池, 测量了温度为296 K, 252 K, 213 K, 173 K时, 3.38 μm附近¹³CH₄分子的四条跃迁谱线的氮气和空气加宽光谱; 首次通过实验获得空气和氮气对¹³CH₄分子的碰撞加宽系数, 以及谱线加宽系数的温度依赖系数. 实验过程中, 利用Voigt线型对所测量的光谱进行拟合. 实验结果表明, 氮气和空气对¹³CH₄分子的碰撞诱导加宽系数随温度的降低而增大; 相同温度下, 氮气对¹³CH₄分子的碰撞加宽系数普遍大于空气加宽系数. 实验数据为地球和外星体大气遥感探测提供了依据.     

Doppler程序对金红石型TiO2的空位缺陷研究

金红石型TiO2是一种非常好的稀磁半导体材料,其自身的本征缺陷与室温铁磁性起源密切相关。本文利用Doppler程序在广义梯度理论（GGA）的基础上,计算了正电子在金红石型TiO2块材中不同缺陷处的湮没寿命。主要包括自由态正电子的湮没寿命,单空位和双空位处束缚态正电子的湮没寿命。并从理论上给出了含有空位缺陷时金红石型TiO2的符合多普勒展宽能谱。     

多勒普加宽斯塔克效应调制分析

用半经典理论分析了含多勒普加宽的斯塔克效应调制，使用密度矩阵近似，导出了吸收线附近ＮＨ３分子的吸收系数和调制度表达式，实验研究了１０．７８４μｍ波长的斯塔克效应调制特性，调制频率１ＭＨｚ时，调制度达到３３％。     

Theoretical analysis of collisional shift and broadening of antiprotonic helium spectral lines

Effect of medium density on shift and broadening of ( ) spectral lines is considered in the framework of binary-collision approximation with an effective ( )–He potential including the long-range attraction and short-range repulsion. Quantum calculations of the scattering phase shifts at reasonable values of the potential parameters allow to explain the main features of the observed density effect on the shape of ( ) spectral lines in low-temperature helium. This revised version was published online in August 2006 with corrections to the Cover Date.     

Lineshape analysis of stimulated Raman spectra of the near‐nozzle region of free jet expansions

An anomalous lineshape of stimulated Raman spectra obtained from the region very close to the nozzle of supersonic pulsed expansions of nitrogen is presented. High‐resolution Raman spectra of the Q branch of the fundamental vibration mode of N₂ have been recorded from two different nitrogen expansions at T₀ = 295 K and P₀ = 1.5–3.5 bar, the lasers crossing the jet axis in the range z/D = 0.25–1.25, where D is the effective nozzle diameter. The combination of Doppler shifts and strong gradients of density and temperature in the near‐nozzle region yield an inhomogeneous broadening and a double peak structure of the recorded Raman line profiles. The comparison of the experimental results with the simulation of the Raman spectrum from this region provides valuable information about the near‐nozzle flow field. The lineshape described here is different from another reported previously in the literature, which is based on a depletion of the density of free molecules on the axis due to condensation. Copyright © 2009 John Wiley & Sons, Ltd.     

嵌入锂原子的zigzag型单壁碳纳米管的电子传导特性

运用基于第一性原理的密度泛函理论（DFT）的非平衡格林函数（NEGF）方法对Li原子嵌入后的zigzag型单壁碳纳米管(SWCNT)的电子输运性质进行了研究.在构建和优化了Li原子嵌入的zigzag型单壁碳纳米管的电子输运模型后,研究了该系统的电子传输概率、能态密度、电子透射谱,还研究了电子能量和偏置电压设置与变化对其电子输运特性的影响.结果显示zigzag型单壁碳纳米管嵌入Li原子后,电子输运特性发生了较大变化,具有电子输运拓宽效应和量子台阶复苏效应. 关键词： Li原子 碳纳米管 电子输运 拓宽效应     

全光纤高效超连续谱光源实验研究

 报道了一个全光纤的高效率超连续谱产生系统,系统采用增加一段匹配光纤的办法解决增益光纤和光子晶体光纤直接熔接损耗较大的问题,并且对匹配光纤和光子晶体光纤熔接对准过程进行实时监控,使熔接损耗降到最低,从而实现了较高的全系统转换效率(76%)和较好的光束质量。实验研究了超连续光谱展宽的过程,结果显示：超连续谱展宽的初始阶段,拉曼效应和自相位调制效应起主要作用,光谱呈现长波方向展宽较多的非对称性,并出现明显的拉曼斯托克斯峰;光谱继续展宽时,满足相位匹配条件的四波混频开始起作用,拉曼效应产生的加宽光谱成分作为四波混频参量过程的泵浦,使光谱开始向长波和短波两个方向扩展。     

双路光谱展宽的钛宝石飞秒光学频率梳系统

对中国计量科学研究院研制的第一代基于钛宝石飞秒激光器的光学频率梳系统进行了改进和优化. 通过对激光器重复频率、光谱展宽以及拍频信号探测等方面的改进,有效地降低了光谱展宽的复杂性,提高了飞秒光学频率梳系统的稳定性和激光频率测量的便捷性. 采用该光学频率梳系统对碘稳频532 nm和碘稳频633 nm激光绝对频率进行了测量,测量结果在国际推荐值的不确定度范围之内. 关键词： 光学频率计量 飞秒光学频率梳 光谱展宽     

纳米Fe3 O4 颗粒的正电子湮没谱学研究

测量了磁性纳米Fe₃O₄颗粒的X射线衍射谱(XRD)、正电子湮没寿命谱(PALS)和符合多普勒展宽谱(CDBS),研究了不同压力和退火温度对磁性纳米Fe₃O₄颗粒物相、电子结构、缺陷及电子动量分布等的影响. XRD,PALS,CDBS测量结果表明:纳米Fe₃O₄颗粒的缺陷浓度随压力的增加而增大,但物相和缺陷类型并未发生变化;磁性纳米Fe₃O_{4< 关键词： 正电子 3}O₄')" href="#">Fe₃O₄ 寿命谱 多普勒展宽谱     

Improved convergence of a non-perturbative semi-classical pressure broadening model

It is shown that by including the second term of Magnus expansion, improved convergence can be achieved for the non-perturbative pressure broadening formalism proposed by Neilson and Gordon (J. Chem. Phys. 58 (1973) 4131). The present method was applied to the line broadening calculations of CO in a bath of Ar.