大气压基体辅助激光解析离子源的研制及其与高分辨飞行时间质谱仪的联用

介绍了自制大气压基体辅助激光解析离子源的原理及结构.考察了该离子源与高分辨率垂直引入式飞行时间质谱仪联用后的性能.实验结果表明,仪器灵敏度、质量分辨率和精度等达到了较高水平.     

小型飞行时间质谱装置的构建

飞行时间质谱仪（TOF MS）在准确度、分辨率、灵敏度、质量上限、分析速度等方面具有优势,在生命科学等领域发挥着重要作用。目前商用飞行时间质谱仪已经比较成熟,但仪器尺寸普遍较大,且价格昂贵,维护困难;而小型仪器则面临分辨率较低等问题。提高小型飞行时间质谱仪的分辨率,降低购置成本和维护成本,对于飞行时间质谱仪的大范围推广有着重要意义。本工作构建了一套分辨率较高的小型飞行时间质谱装置,包括真空系统、离子源、锥孔、引出加速及偏转模块、离子反射镜模块、探测器模块、电路系统等。该仪器主体尺寸较小（0.5 m×0.5 m×0.7 m）,飞行管长度仅0.25 m。由于采用了模块化设计思路,各个模块之间独立封装,仪器的维护、升级工作简单易行。该仪器的关键模块采用创新设计,使得在m/z 2 000处分辨率可达4 200。     

飞行时间质谱仪测控网络及分析器高压程控电源的设计

为了实时有效地控制飞行时间质谱仪的各工作模块,简化各系统之间的通讯方式,提出了基于CAN总线的测控网络,各模块集成了微处理器和CAN总线接口,作为CAN总线中的节点,在仪器内部实现点对点的数据传输,从而提高了仪器的可扩展性.此外,为给飞行时间质谱仪分析器提供连续可调、均匀稳定的高精度电场,提出了一种模块化、小型化的电源...     

能同时检测正负离子的激光离子源质谱计

本文介绍一台能够同时检测激光等离子体中的正负离子的飞行时间质谱仪,它不仅具有较高的分析测试效率,而且能够研究激光等离子体中正负离子在组分、丰度等方面的相关性.初步测试显示了该仪器对正负离子都具有很高的灵敏度和质量分辨能力.     

高分辨率高灵敏度飞行时间质谱仪

本文讨论了提高飞行时间质谱仪的分辨率和灵敏度的基本问题，给出了仪器的结构设计。实验表明，其分辨率Ｒ＞２５００，灵敏度为３０Ａ／Ｐａ。     

辉光放电飞行时间质谱仪离子光学系统的改进及其性能的初步测试

本文介绍一种经过改进的离子光学系统，并用于垂直引出式辉光放电飞行时间质谱仪。初步研究了它的性能，包括吸引锥、透镜、直流四极杆、狭缝电位变化时对仪器灵敏度与分辨率的影响，并检测了黄铜样品谱图。结果表明，该系统不仅能有效地提高离子的传输效率，提高灵敏度，而且能减少高手的空间分散，改善分辨本领，同时对于质谱仪的真空系统性能的提高也有很大的作用。     

高分辨率电喷雾电离飞行时间质谱仪测定大豆磷脂中的磷脂酰胆碱

首次实现了国内用自制高分辨率电喷雾电离飞行时间质谱仪(ESI-TOF-MS)检测大豆磷脂中的磷脂酰胆碱(PC),共检测出了52种磷脂酰胆碱.实验证明,高分辨率ESI-TOF-MS具有定性速度快、灵敏度高、精确度好的优点,是目前磷脂检测的最为有效的工具.     

高效液相色谱检测器-飞行时间质谱的研制

飞行时间质谱仪(TOFMS)是所有质谱仪分析速度最快(微秒级)、质量检测范围最宽、离子传输率最高的一种质谱仪.尤其是近几年来TOFMS的在分辨率上有质的飞跃(优于104).近年来,随着国际上对生物化学、基因蛋白质工程和生物制药等领域的不断深入,作为在该领域中重要的分析研究工具,飞行时间质谱仪(TOFMS)以它微秒级的快速检测速度、高离子传输率、高灵敏度和精度,以及理论上无质量检测上限等众多优点,而逐渐成为质谱仪家族中发展势头最为迅猛的仪器.     

激光溅射离子源垂直引入式飞行时间质谱仪的研制

介绍了两台自行研制的激光溅射离子源垂直引入式飞行时间质谱仪(LAI-oa-TOFMS),相比于其他固体样品直接分析法,该仪器具有样品预处理简单、样品更换速度快(数分钟)、可进行微区分析、谱图干扰峰少和绝对灵敏度高(10-15g级)等众多优点。两台质谱仪的最佳质量分辨率分别达到7 000和4 000(FWHM)。重点对比分析了不同样品的电离方式和离子传输系统对仪器性能的影响。     

高效液相色谱检测器——高分辨飞行时间质谱仪的研制

本文研制的质谱仪是具有电喷雾离子源和射频四极杆接口的高分辨飞行时间质谱仪（ESI-QQQ-TOF-MS）。该仪器的特点如下：采用可三维调节、带有加热雾化气的电喷雾源液质联用接口；采用由三组四极杆组成、可有效调制离子束的离子光学系统；采用正负双脉冲推斥和垂直引入方式；采用经优化设计的二级有网反射器。该仪器分辨本领优于11 000（Full Width at Half Maximum, FWHM），质量测定精度优于10×10^-6，最低检测限低于3 fmol/μL。可作为高效液相色谱优良的质谱检测器。     

Diffraction effects in inner-shell ionization edges

The influences of elastic on inelastic scattering under systematic-row conditions are described in a simple way. A kinematic approach, superposing inelastic intensity-distribution profiles centred at different Bragg spots is shown to be qualitatively correct but quantitatively unsatisfying. A model considering Bragg reflection of the fast electron before and after the inelastic scattering process and thus introducing interference effects is in good agreement with experimental results. Experimentally, we recorded inelastic intensities in the diffraction pattern of an epitaxial copper foil using a PEELS spectrometer and observed energy filtered extinction contours of a copper crystal.     

Plasma-assisted catalytic ionization using porous nickel plate

Hydrogen atomic pair ions, i.e., H(+) and H(-) ions, are produced by plasma-assisted catalytic ionization using a porous nickel plate. Positive ions in a hydrogen plasma generated by dc arc discharge are irradiated to the porous plate, and pair ions are produced from the back of the irradiation plane. It becomes clear that the production quantity of pair ions mainly depends on the irradiation current of positive ions and the irradiation energy affects the production efficiency of H(-) ions.     

An absolute ionization monitor of proton beams

A monitor of a 1-GeV proton beam is described. An ionization chamber composed of two sections with interelectrode gaps differing in length is used as a detector. Air at atmospheric pressure is the working gas of the detector. The error in measuring the number of protons in fluxes ranging from 10⁶ to 5 × 10⁹ s⁻¹ is 5% or less.     

A low-voltage ionization chamber for the ITER

An ionization chamber with an operating supply voltage of 10 V has been designed for use at the ITER. The sensitivity of the chamber filled with air at atmospheric pressure is 100–200 times higher than the sensitivity of the chamber pumped down to a pressure of 10⁻³–10⁻⁴ Torr. It is shown that application of the supply voltage modulation technique allows the pickup noise to be substantially reduced; as a result, the amplifier can be located at a large (70–100 m) distance from the chamber. Results of the experiments aimed at testing this technique on the T-10 facility are described. Original Russian Text ? Yu.V. Gott, M.M. Stepanenko, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 117–121.     

Development and applications of surface-activated chemical ionization

This review regards the recently developed ionization source named surface-activated chemical ionization (SACI) that employs an interaction with a surface placed at low voltage for the activation of the ionization of sample molecules to increase the sensitivity in the analysis of various compounds of biological and clinical interest. These results are due to the strong chemical noise decrease and the increase of ionization efficiency. This ionization source has been employed for the analysis of various compounds of different molecular mass and polarity (addicted and pharmaceutical drugs, amino acids, steroids, peptides, and proteins). The SACI development theoretical mechanism, benefits, disadvantages, applications, and future developments are reported and discussed.     

Orientation dependence of ionization edges in EELS

Anisotropy in the density of unoccupied states can be detected in the fine structure of ionization edges in angle-resolved EELS. It is shown that in a crystal an interference term occurs in the inelastic signal, and how it relates to electron channeling and site selection. The combination of orientation and site selection induces subtle variations in the ELNES. It is shown how this technique can be used to analyze local anisotropy related to the point group of the target atom. A second example shows how to extract non-dipole transitions at small scattering angles.     

Eliminating the induction effect in grid ionization chambers

The influence of the grid shielding inefficiency on the total energy resolution of parallel-plate ionization chambers with electron collection is analyzed. The design of a chamber is proposed and investigated, in which the influence of the induction effect on the energy resolution is substantially suppressed and, at the same time, the grid manufacturing technology is simplified.