电荷测量与时序逻辑电路的研究

中国科学院近代物理研究所大科学工程HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）已建成并处于调试和验收阶段，实验探测系统也正在建设当中。CSRm实验探测系统由外靶系统和内靶系统构成，主要用于核物理实验研究。CSRm TOF测量系统是现阶段CSRm实验探测系统的主要任务之一。 针对CSRm TOF测量系统电荷测量部分，论文阐述了一种采用前端ASIC-SFE16（Saclay Front End 16）芯片实现电荷测量的新型方法。它替代了采用分立元件和电子学插件构建系统的传统方法，着重解决了近代核物理实验中越来越突出的多路多道需求和高性能指标要求。根据我所多丝漂移室探测器的实际情况，我们设计了基于ASIC芯片的电荷测量前端电路板，结合中国科技大学的时间测量数字获取板，我们初步完成了对系统软硬件的测试，给出的实验室性能测试指标，为其在实验探测系统中的应用奠定了坚实的基础。 同时为了选出测量中的有用事例，需要进行事例判选，因此我们研制了多路延迟/脉宽调节时序逻辑电路，主要功能是针对提供的多路逻辑时序信号进行延迟和脉宽调节，支持NIM负信号输入和输出。 文中最后一部分论述了根据在调试过程中出现的实际问题所提出的解决方法，主要是针对电路的可靠性设计和噪声的处理

HPLUS前角区径迹探测器的设计和模拟

在HIRFL-CSR上筹建的兰州强子谱仪（HPLUS）中，前角区径迹探测器（FTD）对于粒子鉴别以及系统的触发都是非常重要的部分之一。计划中的FTD是由五块平面型的多丝漂移室组成，主要用来测量在前角区出射的带电粒子的径迹 （和能损），实现粒子动量测量和粒子鉴别，而联合其它探测器（如TOF和TPC）则可能提高由于取样数限制的粒子鉴别。实现探测器构型的优化和对拟建装置上物理目标的可行性预研是模拟工作的重要目的。快模拟是对拟建装置进行快速优化的有效方法。在Geant4环境对拟建装置的细致模拟，是进一步优化探测器结构、充分的估计探测器整体性能的必要步骤，为将来的谱仪的制造和可能的物理实验提供可靠的参考。 本论文的主要工作包括以下两个方面。（1）在HPLUS概念设计的基础上，发展了局域化的多径迹查找和径迹重建算法，对产物在前角区分布的典型反应道pp→pp+φ(→K+K-)进行了可行性预研，得到FTD对φ的几何覆盖率为83.5%，由于漂移室空间分辨对的动量分辨的贡献为1.3%，并在考虑了本底道pp→pp+K+K-的影响下，重建了φ的不变质量谱，得到φ峰宽度和信噪比分别为1.51MeV和4.36。在考虑到前角区径迹探测器的占有空间和探测要求的情况下对HPLUS构型做出了一定的优化，为全模拟提供了一组FTD参数。（2）基于快模拟得到的参数和参考了PANDA探测器漂移室的情况下，完成了FTD的初步设计并对其中的物质分布进行了预算，通过经验公式得到FTD的空间分辨和多次散射对K+动量分辨的贡献为1.34%和0.34%。在HPLUS模拟平台上，用GDML语言完成了对前角区径迹探测器的构建

寻找质子滴线核25P、26S

原子核的滴线是指原子核沿同位旋自由度从束缚态核变为非束缚态核的边界，也是原子核存在的极限。质子滴线是在缺中子方向的边界，中子滴线是在丰中子方向的边界。到目前为止，S 同位素的质子滴线核被认为是27S，P 同位素的质子滴线核是26P，虽然有实验发现了25P，但是还没有被重复，需要进一步的确认。而理论模型计算表明束缚态的26S 和25P 是存在的，因此寻找25P、26S 一直是一个很有意义的课题，如果能够确认25P 和26S 的存在与否，不仅可以检验相关理论模型的正确性，确认原子核在同位旋自由度上的存在极限，帮助人们对核力的进一步深入认识，而且对于天体物理，宇宙演化及元素的形成等都有着重要的科学意义。本论文介绍了2008 年6 月在兰州放射性束流线(RIBLL)上进行的专对25P、26S存在与否寻找的实验，并分析了实验数据。实验使用80.387MeV/u32S 初级束轰击9Be 初级靶，经过RIBLL 对次级束产物进行了分离以后，利用Bρ+ΔE+ER+TOF 联合鉴别的方法对次级束产物了鉴别。重离子在CsI 探测器中沉积能量与光输出响应之间满足一定的经验公式，本文利用RIBLL 上的次级束产物刻度了粒子在CsI(Tl)探测器中的能量沉积与光输出响应的光输出曲线，通过一组刻度数据可以确定核素在CsI 探测器中光输出响应道数，发现粒子在CsI(Tl) 探测器中信号的ADC 读出与CsI(Tl)探测器的光输出(QDC 读出)具有很好的线性关系。论文最后比较了实验统计数据与EPAX 经验公式计算结果，并利用计算结果与实验数据分析结果估算了25P、26S 的半衰期上限

多电荷态硫离子与氦原子和氢分子碰撞中的多电子转移过程研究

本工作采用反冲离子飞行时间技术和散射离子位置灵敏探测技术，实验研究了Sq+离子与He、H2碰撞中的多电子转移过程和分子离子的碎裂现象。研究了转移电离截面与单电子俘获截面比值和入射离子损失一个电子和两个电子的情况下，靶原子双重电离与单重电离的截面比值随入射离子能量和入射离子电荷态的变化规律，并对不同的碰撞体系的结果进行了比较。研究发现：在本工作研究的入射离子能区，对于HZ分子靶，双电子俘获自电离反应道：S2+H2→S(q-l)+2H++e-。是转移电离过程的主要贡献，而直接转移电离的贡献可以忽略；随着入射离子电荷态的增加，双电子俘获自电离的贡献增加，直接转移电离的贡献逐渐减小，但双电子俘获自电离的贡献的增加比理论预言的要慢。建立了蒙特卡罗程序模拟离子与分子碰撞中产生的具有不同的初始动能的离子碎片的飞行时间谱，深入分析和研究了Sq＋与H2分子碰撞中产生的H2+的解离过程和库仑爆炸过程，以及H＋碎片的能量分布。模拟结果与实验测量到的TOF谱的分析比较说明：在Sq＋与H2分子碰撞实验中，库仑爆炸是产生H+的主要反应道，而氢分子离子H2+发生解离产生H+的反应道相对很弱。

重离子耗散反应激发函数振荡结构的实验研究

直到八十年代中期，人名才发现耗散反应激发函数中存在振荡结构这种新现象。通过对激发函数振荡结构能量自关联函数的研究是获得复合核能级宽度的一个重要手段，Brick推广了Ericson的复合核统计理论，并成功地用于分析耗散反应激发函数振荡结构的研究，提取相应的能量相关宽度Г。本文报道了19F+51V耗散反应激发函数振荡结构的实验研究结果，用能级部分重叠模型对角动量相干引起的截面涨落、能量自关联函数进行了计算分析。实验中采用ΔE-E粒子鉴别方法和飞行时间TOF测量技术队102.25Mev~109.5Mev19F+51V反应类弹产物同时进行电荷和质量鉴别。首次在各个元素、同量异位素（质量数A为常数）和同位素的耗散反应激发函数中观察到振荡结构，并进一步证实了反应产物的各个出射道之间存在着相关。检验了用小角度弹性散射计数做相对归一对激发函数振荡结构研究可能造成的影响。分别采用能量自关联函数方法和谱密度方法提取了各个激发函数的能量相关宽度Г，其值大小为~350kev，并与出射道的电荷数Z、质量数A和中质比N/Z有很大的依赖关系，表明出射产物与入射弹核的差别越打所需的反应时间久越长。首次得到了Г随N/Z值变化的趋势，Г随N/Z的分布为Gauss型，通过分析分布的宽度得到其大小随相互作用时间的增长而线性增大的结果，并进一步提取了电荷扩散系数，证实了反应系统已达到电荷平衡。Г的数值随出射角的增大有减小的趋势。双核系统的转动造成了Г随出射角的变化关系，实验提取的双核系统平均角速度发生了较强的阻尼。用能级部分重叠模型在适当的精度内对激发函数和能力自关联函数进行了模拟。计算分析说明入射道的动能大多数转化为双核系统的转动能，只有较少部分转化为双核系统的内禀激发能，双核系统被激发到能级密度不太大的区域，能级之间的部分重叠引起截面的振荡行为。入射道角动量的相互干涉、双核系统能级的部分重叠和出射道的相互关联使得耗散反应的激发函数表现出其特有的规律性。

Characterization of complex hydrocarbons in cigarette smoke condensate by gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

Gas chromatography-mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to assign the components from GC x GC-TOF-MS analysis. The distributions of aliphatic hydrocarbons and aromatics were also investigated. Over 100 isoprenoid hydrocarbons were detected, including carotene degradation products, phytadiene isomers and carbocyclic diterpenoids. A total of 1800 hydrocarbons were tentatively identified, including aliphatic hydrocarbons, aromatics, and isoprenoid hydrocarbons. The identified hydrocarbons by GC x GC-TOF-MS were far more than those by GC-MS. (C) 2004 Elsevier B.V. All rights reserved.

The PPh3 ligand modified Rh/SiO2 catalyst for hydroformylation of olefins

A novel family of hybrid catalyst with high turnover frequency (TOF) and high selectivity towards aldehydes for hydroformylation of olefins could be successfully approached through direct coordination with the PPh3 ligand to the highly dispersed Rh metal particle precursors. A further advantage is that the catalyst is easily prepared and recyclable. The results revealed that hydroformylation of olefins to aldehydes dominantly took place on the surface of PPh3 ligand modified Rh metal particles of the hybrid catalyst. It was found that the formation of chemical coordination bond between the Rh metal particles and the lone-pair electron of PPh3 was evident through the TG and P-31 NMR measurement. Moreover, the addition of PPh3 onto the Rh/SiO2 exert a significant influence on the adsorption state of reactant CO, H-2 and C2H4 on the PPh3-Rh/SiO2 sample, which probably lead to good catalytic performances for hydroformylation of olefins. (C) 2004 Elsevier B.V. All rights reserved.

State-to-state dynamics of elementary chemical reactions using Rydberg H-atom translational spectroscopy

In this review, a few examples of state-to-state dynamics studies of both unimolecular and bimolecular reactions using the H-atom Rydberg tagging TOF technique were presented. From the H2O photodissociation at 157 nm, a direction dissociation example is provided, while photodissociation of H2O at 121.6 has provided an excellent dynamical case of complicated, yet direct dissociation process through conical intersections. The studies of the O(D-1) + H-2 --> OH+H reaction has also been reviewed here. A prototype example of state-to-state dynamics of pure insertion chemical reaction is provided. Effect of the reagent rotational excitation and the isotope effect on the dynamics of this reaction have also been investigated. The detailed mechanism for abstraction channel in this reaction has also been closely studied. The experimental investigations of the simplest chemical reaction, the H-3 system, have also been described here. Through extensive collaborations between theory and experiment, the mechanism for forward scattering product at high collision energies for the H+HD reaction was clarified, which is attributed to a slow down mechanism on the top of a quantized barrier transition state. Oscillations in the product quantum state resolved different cross sections have also been observed in the H+D-2 reaction, and were attributed to the interference of adiabatic transition state pathways from detailed theoretical analysis. The results reviewed here clearly show the significant advances we have made in the studies of the state-to-state molecular reaction dynamics.

Multiphoton ionization and ab initio calculation studies of pyridine-water mixed clusters using time of flight mass spectrometer

Multiphoton ionization of binary mixed clusters (C5H5N)(x)-(H2O)(y) at 532, 355 and 266 nm laser wavelengths has been investigated using TOF mass spectrometer. The experiments showed that almost all the products were protonated ions, At 532 and 355 nm, the products were mainly protonated pyridine clusters (C5H5N)(n)-H+, while at 266 nm, mixed binary cluster ions (C5H5N)(m)- (H2O)(n)-H+ appeared. It was found that the abundance of the [(C5H5N)(3)-H2O-H](+) ions was abnormally high. The calculation indicated that the ion [(C5H5N)(3)-H2O-H](+) is Of a kind of magic number structures with C-3v symmetry. A stepwise reaction mechanism is suggested that photoionization is followed by dissociation. (C) 2001 Elsevier Science B.V. All rights reserved.

Mass resolved MPI spectra of methyl iodide in the 430-490 nm region

The mass resolved multiphoton ionization (MPI) spectra of methyl iodide were obtained in the 430-490 nm region using a time-of-flight (TOF) mass spectrometer. They have the same vibrational structure, which testifies that the fragment species, in the wavelength region under study, are from the photodissociation of multiphoton ionized molecular parent ions. Some features in the spectra are identified as three-photon excitations to 6p and 7s Rydberg states of methyl iodide. Two new vibrational structures of some Rydberg states are observed. The mechanism of ionization and dissociation is also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Matrix-assisted laser desorption/ionization mass spectrometry using porous silicon and silica gel as matrix

Porous silicon powder and silica gel particles have been applied as inorganic matrices for the analysis of small molecules in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS). In contrast to conventional MALDI-TOFMS, the signal interference of low-molecular analytes by the matrix has been eliminated. Almost no fragmentations of the analytes were observed. Effects of various factors, such as the particle and pore size, the suspending solution, and sample preparation procedures, on the intensity of mass spectra have been investigated. The pore structure of the inorganic matrix and penetration of the analytes into the pores must be optimized for effective desorption and ionization of the analytes. Matrices (DHB and HCCA) were covalently bound to silica gel for improvement of spectrum intensity. Copyright (C) 2001 John Wiley & Sons, Ltd.

三聚氰胺的基质辅助激光解吸/电离飞行时间质谱研究

Oxidized carbon nanotubes are tested as the matrix for analysis of the melamine by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Traditional MALDI matrix are not suit for analysis of the low molecular compounds due to the interference associated to the matrix clusters. Oxidized carbon nanotubes can transfer energy to the analyte under the laser irradiation, which makes analyte well ionized or desorbed. Moreover, the interference of the intrinsic matrix ions can be eliminated. Melamine as the a toxic additive which had been added in the milk powder, then it is necessary to establish a new method for detection of the melamine rapid and sensitive.

Selective hydrogenation of citral catalyzed with palladium nanoparticles in CO2-in-water emulsion

CO2-in-Water (C/W) emulsion was formed by using a nonionic surfactant of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (P123), and palladium nanoparticles were synthesized in situ in the present work. The catalytic performance of Pd nanoparticles in the C/W emulsion has been discussed for a selective hydrogenation of citral. Much higher activity with a turnover frequency (TOF) of 6313 h(-1) has been obtained in this unique C/W emulsion compared to that in the W/C microemulsion (TOF, 23 h(-1)), since the reaction was taking place not only in the surfactant shell but also on the inner surface of the CO2 core in the C/W emulsion. Moreover, citronellal was obtained with a higher selectivity for that it was extracted to a supercritical carbon dioxide (scCO(2)) phase as formed and thus its further hydrogenation was prohibited. The Pd nanoparticles could be recycled several times and still retain the same selectivity, but it showed a little aggregation leading to a slight decrease in conversion.

有机半导体中载流子迁移率的测量方法

本文简要地介绍了有机半导体中载流子迁移率的几种模型,着重阐述了测量有机半导体中载流子迁移率的各种方法的测试原理。主要有如下几种:稳态(CW)直流电流-电压特性法(steady-state DC JV),飞行时间法(time of flight,TOF),瞬态电致发光法(transient electroluminescence,transient EL),瞬态电致发光法的修正方法即双脉冲方波法和线性增压载流子瞬态法(carrier extraction by linearly increasing voltage,CELIV),暗注入空间电荷限制电流(dark injection space charge limited current,DI SCLC),场效应晶体管方法(field-effect transistor,FET),时间分辨微波传导技术(time-resolved microwave conductivity technique,TRMC),电压调制毫米波谱(voltage-modulated millimeter-wave spectroscopy,VMS)光诱导瞬态斯塔克谱方法(photoi...

Alternating copolymerization of carbon dioxide and propylene oxide catalyzed by (R,R)-SalenCo(III)-(2,4-dinitrophenoxy) and Lewis-basic cocatalyst

A binary catalyst system of a chiral (R,R)-SalenCo(III)(2,4-dinitrophenoxy) (salen = N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-diphenylethylenediimine) in conjunction with (4-dimethylamino)pyridine (DMAP) was developed to generate the copolymerization of carbon dioxide (CO2) and racemic propylene oxide (rac-PO). The influence of the molar ratio of catalyst components, the operating temperature, and reaction pressure on the yield as well as the molecular weight of polycarbonate were systematically investigated. High yield of turnover frequency (TOF) 501.2 h(-1) and high molecular weight of 70,400 were achieved at an appropriate combination of all variables. The structures of as-prepared products were characterized by the IR, H-1 NMR, C-13 NMR measurements. The linear carbonate linkage, highly regionselectivity and almost 100% carbonate content of the resulting polycarbonate were obtained with the help of these effective catalyst systems under facile conditions.