激光共振电离光谱技术是一种利用一路或多路激光将待测原子选择性共振激发与电离, 通过测量离子信号来研究原子能级结构的光谱技术。 研建了一套激光共振电离光谱装置, 用于原子高激发态能级结构参数的测量。 分别从该装置的总体结构、 关键技术和应用实例等方面进行了详细介绍。 该套装置主要包括高调谐精度的染料激光器系统、 高效的激光离子源系统和高分辨率的飞行时间质量分析器。 染料激光器系统包括3台多纵模可调谐染料激光器和1台单纵模可调谐染料激光器, 均为脉冲工作方式, 重复频率为10 kHz, 泵浦源均为532 nm的Nd∶YAG固体激光器。 激光离子源系统包括原子化源、 激光与原子相互作用区和离子光学透镜组三部分组成, 样品在原子化源中被电加热实现原子化, 喷射出的原子被激光选择性激发、 电离, 产生的离子被离子传输透镜整形成能量分散小、 束窄的离子束。 飞行时间质量分析器采用了反射式结构设计、 脉冲垂直推斥技术和偏转板调节技术。 利用此装置, 实验测定了U原子的自电离态光谱, 获得了U原子一条较佳的三色三光子共振电离路径, 对应激光的波长分别为591.7, 565.0和632.4 nm。 此系统还可用于测量同位素位移和原子超精细结构等参数。 另外, 由于此系统中联用了质量分析器, 因此可用于样品多元素分析、 痕量元素分析、 同位素丰度分析。

Laser resonance ionization spectroscopy (LRIS) is one of the element-selective spectroscopy methods, which aims to study the energy level parameters of the atom by measuring the ion signal. The atom is selectively excited and ionized by one or more lasers in LRIS. A set of totally domestic LRIS apparatus was built, which was used for measuring the parameters of the atomic high lying states. The overall structure, main technique and application of the LRIS apparatus were described in detail. The LRIS system was consisted of high precision tunable dye lasers, high efficiency laser ionization system and high resolution time of flight mass analyzer (ToF-MA). There were three sets of multimode dye laser and one set of single longitudinal mode dye laser, which were pumped by 532 nm Nd∶YAG laser. The repetition frequency of the dye laser was 10 kHz. The laser ionization system contained atomization source, atom and laser interreaction region and ion lens. The atom sprayed from the atomic source was selectively excited and ionized by lasers, and then was reshaped as ion beam with small divergence angle and narrow beam width by ion lens. The reflecting structural design, pulsing vertical repulsion technique and deflecting plate adjusting method were adopted in the ToF-MA. Based on the laser resonance ionization spectroscopy technique, the auto-ionization spectrum of uranium atom was measured with the aid of this apparatus. An efficient three-color-three-photon resonance ionization scheme of uranium atom was obtained. The center wavelengths of the lasers were 591.7, 565.0 and 632.4 nm, respectively. The isotopic shift and the hyperfine structure also can be analyzed by this apparatus. In addition, as result of the mass analyzer employment, the proposed apparatus can be used to analyze the sample component, trace element concentration, and isotopic abundance.