绝热近似下的原子光电离

将 Landau 绝热近似理论,用于处理强光场中原子光电离过程,得到了原子光电离几率的解析表达式.将这一表达式同著名的 Keldysh 公式比较,在特定的条件下,它可约化为 Keldysh 公式;同模型理论比较,它又是模型理论的近似结果.还讨论了绝热近似结果的2个可能的改进途径.     

芳香氨基酸及其肽光电离、SO*-4氧化与光敏化过程的比较研究

运用激光闪光光解瞬态吸收光谱研究了色氨酸 (Trp)、酪氨酸 (Tyr) ,苯丙氨酸 (Phe)和二肽 (Trp Tyr)光电离和被SO· - 4单电子氧化的过程 ,表征了反应过程中生成的自由基 ,并与丙酮光敏化生成的自由基进行了比较。三者不同之处是 ,Trp和Tyr光电离分别生成氮中心的吲哚自由基和酚氧自由基 ;丙酮光敏化除生成上述自由基外 ,在敏化Trp光解体系还观察到Trp激发三重态 ,丙酮三重态与Phe没有作用 ;在SO· - 4单电子氧化体系 ,分别在Trp的吲哚环、Tyr的苯环上加成生成加成产物 ,其中Trp尤为显著 ;Phe的光电离与SO· - 4氧化体系结果一致。在二肽Trp Tyr的光电离和光敏化体系中观察到自由基的转变过程 ,Trp/N· Tyr→Trp Tyr/O·即分子内的电子转移过程 ;而SO· - 4单电子氧化体系没有观察到这种转变     

光离子化信号检测仪的若干特性研究

根据微弱光电离信号的检测需要,开发出光新型离子化信号检测仪.给出仪器工作原理和硬件核心设计,集气体光电离检测、微弱信号收集、信号检测与数据处理等技术于一体.讨论了仪器电离源和实验样品的选择,并设计出系统实验装置.利用国家标准物质研究中心配制的标准气体和检测仪进行联测,检验了极低浓度挥发性有机化合物的检测效果,并估算了仪器的灵敏度和检测限,效果令人满意.     

碱金属原子光电离截面的计算

作者用多体微扰理论（MBPT），对开壳层钠和钾原子的最外满壳层单光子电离过程进行了研究和理论计算。利用多体微扰理论的Goldstone图示法，对主要的电子关联作用进行了分析，给出了完整的从零级到二极的图示，其中二级近似包括了The random-phase approximation(RPA)及重要的Brueckner-orbital(BO)和Structure-radiation(SR)关联。考虑了分波截面在不同近似级下的变化。给出了截面的长度形式和速度形式，这两种形式符合较好，而且总截面与实验值亦符合较好。     

钴原子激发态光电离的实验研究

文章报道了在300-310nm波长范围内3d过渡金属Co原子共振增强多光子电离(REMPI)的实验研究结果.实验中采用激光烧蚀和高压脉冲超声分子束相结合的技术制备等离子体,获得的等离子体与探测激光作用形成光电离产物,由飞行时间质谱仪对光电离产物进行甄别.通过分析光电离产物产额随探测激光强度的变化关系,得到了Co原子激发态的绝对光电离截面.     

Photoionization of aromatic amino acid at different pH values

The photoioization of aromatic amino acid in solutions of different pH values were investigated by 248 nm laser flash photolysis. The results showed that the photoionizations of tyrosine and tryptophan were affected by pH value of solution, but phenylalanine was not. The ionization was in favor of monophotonic process at high pH value and of biphotonic process at low pH value. The mechanisms of pH effect on photoionization of tyrosine and tryptophan were the deprotonation of phenolic hydroxyl group and the deprotonation of＞NH on the indole ring respectively. Our results explain the discrepancy of values for the yield of hydrated electron obtained by other investigators.     

混合气体介质中三倍频辐射的产生实验

将355 nm光通过单一的X e或者X e-A r混合气体介质产生118 nm辐射,记录不同气体压力下光激励丙酮光解的质谱图,通过监控丙酮分子离子峰(m/z=58)的强度来掌控118 nm光的产生效率.结果表明:在实验光学器件、激光光强相同的条件下,混合气体介质中三倍频辐射产生效率比单一气体中强.当混合气体中A r气体压力保持在1.000 kPa,p(X e)¨p(A r)=5.6时,产生的118 nm辐射最强,实现了该实验条件下倍频产生最佳的相位匹配.     

An experimental study of premixed laminar methane/oxygen/argon flames doped with hydrogen at low pressure with synchrotron photoionization

Laminar premixed stoichiometric methane/hydrogen/oxygen/argon flames were investigated with tunable synchrotron vacuum ultraviolet （VUV） photoionizaUon and molecular-beam sampling mass spectrometry techniques. The methane/hydrogen fuel blends with hydrogen volumetric fraction of 0, 20%, 40%, 60% and 80% were studied. All observed flame species, including stable intermediates and radicals in the flames, were detected by measuring photoionization mass spectra and photoionization efficiency （PIE） spectra. Mole fraction profiles of major species and intermediates were derived by scanning burner at some selected photon energies near ionization thresholds. The influence of hydrogen addition on mole fraction of major species and intermediates was analyzed. The results show that the major species mole fraction of CO, CO2 and CH4 decreases with the increase of hydrogen fraction. The mole fraction of intermediates measured in this experiment decreases remarkably with the increase of hydrogen fraction. This would be due to the increase of H and OH radicals by hydrogen addition and the high diffusivity and activity of H radical promoting the chemical reaction. In addition, the increase of H/C ratio with the increase of hydrogen fraction also leads to the decrease of the mole fraction of carbon-related intermediates and contributes to the decrease of unburned and incomplete combustion products.     

类硼离子C+基态光电离的R矩阵计算

使用R矩阵方法,采用三态密耦图像计算了类硼离子C+基态的光电离,并分别给出不同分波及不同过程的截面.计算结果揭示了明显的Rydberg系列共振,并且2D分波对截面的贡献最大.