A New Gas Chromatography Mass Spectrometer Equipped with a Hyperthermal Surface Ionization as a Ion Source

介绍了一种以高温表面电离系统为离子源的新型气相色谱-质谱联用系统。超声速分子束是超声速分子束加速和表面电离的结合。为了考察各参数对该体系运行特性的影响，研究了HSI的电离机理。在文章1中，我们将“γ-因子”定义为用于电离的动能的分数，并通过两个独特的Ek和Ts与测量离子电流的相关性来估计，其中，Ek为分子动能，Ts为表面温度。两种独立方法估计的γ值相当一致。推导出以下结论：(1)动能部分用于电离；(2)能量转换效率（γ值）因分子而异；(3)由于电离能（IE）和表面功函数（ψ）的差异，表面电离所需的能量与能隙有关。在第2篇文章中，描述了一种估计用于激发分子振动度的分子动能转化率的方法。实验结果表明：(1)动能部分用于振动度的激发，转化率可达30%左右。(2)总速率约为初始动能转化为分子内能的50%。(3)表面热能转化为分子内能的概率很小。第三篇综述了近年来有机表面电离的研究进展。这包括(1)基本原理，(2)仪器，(3)响应特性，(4)应用。

A new gas chromatography-mass spectrometer system equipped with a hyperthermal surface ionization (HSI) system as an ion source is described. The HSI is a combination of molecular acceleration in supersonic molecular beam (SMB) and surface ionization (SI). To examine the effect of various parameters on operational characteristics of this system, ionization mechanism of HSI was studied.In the article No.1, we defined the "γ-factor" as the fraction of the kinetic energy used for ionization, and was estimated from two unique Ek and Ts correlation with measured ion current, where, Ek is the molecular kinetic energy and Ts is the surface temperature. The γ values estimated from the two independent methods agreed fairly well. Deduced conclusions are : (1) the kinetic energy is partially used for ionization, (2) the efficiency of energy conversion (γ value) varies from molecule to molecule, (3) the energy required for surface ionization is associated with the energy gap due to the difference in ionization energy (IE) and the surface work function (ψ).In the article No.2, a method to estimate the conversion rate of the molecular kinetic energy used for the excitation of the vibrational degrees in the molecule is described. The experimental results obtained by this method led to the following conclusions : (1) The kinetic energy is partially used for excitation of the vibrational degree, and the conversion rate amount to some 30 %. (2) The total rate amounts to some 50 % of the initial kinetic energy converted to the internal energy of the molecule. (3) There is only a very small probability of surface thermal energy being transferred to the internal energy of the molecule.The article No.3 summarizes the recent development in surface ionization (SI) of organics. This includes (1) basic principles, (2) instrumentation, (3) response characteristics, and (4) applications.