激光诱导Fe^＋和Fe（CO5）离子分子反应机制的实验和理论研究

利用超声分子束和飞行时间质谱检测系统,实验研究了Fe(CO)_5在308nm,355nm和355nm+532nm波长的多光子解离和电离机制.根据实验测量和对于质谱峰结构和峰型的分析分离出由不同机制产生的各离子信号.对于Fe~+和Fe(CO)_5离子分子反应机制及其关于激光波长的依赖关系.从实验和理论两方面做了较深入的研究.     

Investigation of the double diffraction dissociation reaction pp → (pπ+π−) (pπ+π−) at 24 GeV/c

Data from a high-statistics bubble chamber experiment at 24 GeV/c are used to study the double diffraction dissociation reaction pp→(pπ⁺π^?) (pπ⁺π^?) where both protons of the initial state dissociate into pπ⁺π^? systems. Cross section, mass spectra and dσ/dt' distributions have been determined and are compared with the results found for the single diffraction dissociation reaction pp → p(pπ⁺π^?), which have been obtained from the same experiment. All our findings agree well with what is expected from the factorization hypothesis.     

Observation of scaling deviations in the energy distribution of secondary hadrons in inelastic neutrino-proton interactions

An analysis is presented of the z distributions of secondary hadrons produced in 5600 charged current events from a BEBC neutrino-hydrogen experiment. Evidence is presented for scaling deviations in the z distributions and a breakdown of factorization in the single particle inclusive cross sections. The results are consistent with the leading order QCD predictions on the q² dependence of nonsinglet moments of quark fragmentation functions, yielding a value of Λ ≈ 0.6 GeV.     

Measurement of the τ lifetime

Using the 3-prong decays of τ leptons observed at the CELLO detector at PETRA, the τ lifetime is determined to be 4.7(_?2.9^+3.9)×10^?13s.     

532 nm及355 nm丁酮多光子电离质谱研究

利用激光质谱法,采用355 nm及532 nm激光作为光源对丁酮分子进行了多光子电离解离研究,得到了2种波长下丁酮的多光子电离飞行时间质谱图主要有质荷比为1(H ),15(CH3 ),43(CH3CO )的质谱峰.532 nm质谱比较丰富,有较强的质荷比为45的信号,可以认为这是丁酮异构体电离解离得到的产物;同时探测到了质荷比为4,6,8的信号,可能是高价离子.355 nm质谱图相对简单.根据信号比例随激光能量的变化及主要的离子信号,得出了2种波长下主要的解离电离通道.     

800 nm激光作用下碘乙烷的多光子电离解离研究

在800nm飞秒激光作用下对碘乙烷多光子电离解离过程进行了研究,获得了碘乙烷分子的多光子电离飞行时间（MPI-TOF）质谱.光强指数分析表明母体离子主要发生3+3共振增强多光子电离（REMPI）过程.根据部分碎片离子占总离子信号的百分比对激光强度的依赖关系,讨论了碘乙烷的多光子电离解离机制,得出了C₂H₅I分子的多光子电离（MPI）属于母体离子离解阶梯模式.文中分析了母体离子在该波长下主要两条解离通道,其中C-I键的断裂为主要通道.应用高斯03在B3LYP/3-21G基组上计算了两条通道能量的变化,理论进一步验证了实验结果的合理性.     

Software news and updates

A parallel version of the valence bond program TURTLE has been developed. In this version the calculation of matrix elements is distributed over the processors. The implementation has been done using the message‐passing interface (MPI), and is, therefore, portable. The parallel version of the program is shown to be quite efficient with a speed‐up of 55 at 64 processors. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 665–672, 2001