CS2+( 2Πg )的(1+1)光解离动力学研究

在气束条件下,利用483．2nm的激光（3＋1）共振增强多光子电离（REMPI）CS2分子以产生CS2＋离子源,用另一束可调谐激光在424－482nm内,通过对CS2^+(x^2∏g)(1+1)双光子共振解离产生的碎片离子发谱的探测,来获取CS2^+的光解离动力学信息,光解离碎片S^+的激光发谱（PHOFEX）可归属为CS2^+（A^2∏u,3/2(v′=0-4,v′＝v1_(1/2)v2-)←X^2′∏g,3/2(0,0,0))和（A^2∏u,1/2(v=0-4)←X^2∏g,1/2(0,0,0))跃迁,对CS2^+光解离动力学的研究表明,其产生S^+的通道为：（i)CS2吸收一个光子从基态X^2∏g共振激发至A^-2∏u态,（ii)已布居的A^-2∏u态的振动能级和X^2-∏g态的高振动能级产生耦合,（iii)吸收第二个光子从上述耦合的振动能级进一步激发至B^2∑u^+态,再通过B^-2∑u^+态与^4∑^-态间的自旋－轨道相互作用,经由4∑^-排斥态解离产生S^+_CS。     

Ab initio方法研究CH~3+OClO反应的可能通道

利用abinitio方法研究了CH~3+OClO反应的三个可能通道,首次应用UMP2(full)/6-31G(d,p)方法得到各反应物、产物、中间物及过渡态的优化构型和谐振频率;然后采用G2MP2理论计算各通道反应焓变和势垒高度。理论计算表明产物通道CH~2O+HOCl是最可能发生的途径,反应放热为443.80kJ·mol^-^1。可能的反应过程为：CH~3和OClO自由基先经无垒过程生成了一个富能中间物,继而通过较低的势垒解离成HOCl+H~2CO。     

243～263nm CH3COCH3的多光子电离研究

在243－263nm紫外光波段通过质量选择光电离激发谱研究了丙酮（CH3COCH3）的光化学反应通道。分析母体离子CH3COCH3^+和碎片离子CH3CO^+、CH3^+的光电离激发谱和质谱峰宽可以知道：此光波段丙酮分子的光化学反应主要包括了丙酮分子经由（S1,T1）中间态产生母体离子的（1＋1）双光子电离通道,母体离子进一步解离产生碎片离子CH3^+的“光电离－光解离”通道和丙酮分子经由（S1,T1）中间态解离成中性自由基碎片CH3CO后再进一步被双光子电离的“光解离－光电离”通道。由母体离子光电离激发谱双光子阈值波长（255．67nm)给出的丙酮电离势（IP）为（9．696±0．004）eV。     

CS2 分子 1 B2(1 Σ+u )态预解离动力学研究

The predissociation dynamics of CS2 at the g vibrational level of the 1B2(1Σu+) state has been studied, by measuring the predissociation lifetimes from the photofragment CS excitation (PHOFEX) spectrum and the ro vibrational populations of CS fragment from the laser induced fluorescence(LIF) spectrum. It is found that the angular momentum quantum number K of the g level accelerates the dissociation speed of CS2 at the 1B2(1Σu+) state, and increases the branching ratio of S(1D2)/S(3PJ) for the two dissociation channels, CS(X 1Σ+)+S(1D2) and CS(X 1Σ+)+S(3PJ). The dissociation mechanism was discussed based upon the observations.     

弯曲振动对CS_2分子~1B_2(~1Σ_u~+)态预解离寿命的影响

在209.5～216nm,采用光解碎片激发(PHOFEX)谱技术,对CS2分子1B2(1Σ+u)态预解离寿命进行了 考察.测量在超声射流中进行.信号来自解离碎片CS(A1Π,v′=0←X1Σ+,v″=0)Q支带头的激光诱导荧光 (LIF).预解离寿命是通过对谱带进行拟合来提取的.拟合中假定基态转动布居为Boltzmann分布,寿命加宽的转 动谱线为Lorentz线形.通过拟合共获得1B2(1Σ+u)态13个跃迁所对应的预解离寿命,其中6个数据是新得到的. 结果表明,基态振动角动量量子数l或激发态转动角量子数K(K=l)对预解离寿命有明显的影响.对于激发态的 同一振动能级,较大的K对应于较短的预解离寿命.实验中采用可加热的射流喷嘴,用以提高热带激发的强度, 以改善对较大转动角量子数K的影响的考察.     

A classification theorem for complete minimal surfaces in S6 with constant Kähler angles

In the present paper, we shall determine all complete minimal surfaces in the nearly Kähler sphere S⁶ with constant Kähler angles q ? (0, p)\theta \in (0,\,\pi ) and nonnegative curvatures.     

反向泵浦的受激喇曼光声光谱

An improved experiment setup for Stimulated Photoacoustic Raman Spectroscopy（PARS）was reported. The employed two laser beams,unlike general arrangement of propagating in the same direction,counterpropagated with each other. This arrangement can eliminate the limitation that the small Raman shift could not be measured with general arrangement. Therefore,this improved setup was especially useful for measuring the PARS spectrum with small Raman shift,such as the pure rotational Raman spectrum. In the experiment,taking CH4 molecules as a research object,one laser was fixed at 532. 1 nm while another tunable dye laser scanned. The PARS spectrum of CH4 molecules for the v1 ,v2 and v3 bands was recorded in the two wavelength ranges of 625-642 nm and 573-589 nm,and the results agreed well with those obtained by Spontaneous Raman Scattering（ORS）technique,confirming the validity of the improved experimental setup.     

双光子共振四波差频产生的真空紫外激光特性研究

The character of tunable Vacuum-Ultraviolet（VUV）laser generated by two-photon resonant four wave difference frequency mixing in Xenon was studied. The intense VUV laser was generated in the wavelength range of 151-171 nm using 6P［1/2,0］level of Xe atom as the two-photon resonant state. The pulse intensity of VUV laser was estimated to be 0.2 μJ,and the conversion efficiency relative to the wavelength-fixed laser was determined to be 0.1%. The line width of VUV laser was found to be 0.3 cm-1 from the laser-induced fluorescence spectrum of A-X（0,0）rotational line profiles of jet-cooled CO,which was much broader than those of the two employed dye lasers（0. 1 cm-1）,mainly due to the saturation broadening of Xe level by intense laser field. The dependencies of VUV intensity on Xe pressure and two dye laser intensities were also investigated in this experiment.     

四甲基硅的多光子电离光谱和质谱

在半导体生产中常用化学气相沉积(CVD)方法制备纯硅.所用的硅化合物原料中,四甲基硅是很重要的一种.与其它种类相比,它不象硅甲烷那样易爆,又不象卤代硅烷那样有腐蚀性,化学性质是比较稳定的.另一方面,它的分子结构Si(CH_3)_4与一般有机金属化合物类似,具有一定代表性.因此研究这个分子的离解和电离过程,以及光物理与光化学性质,在应用和学术方面都是有价值的。