Wood M, Zhou Y, Brummel C L, Winograd N
Department of Chemistry, Pennsylvania State University, University Park 16802.
Anal Chem. 1994 Aug 1;66(15):2425-32. doi: 10.1021/ac00087a004.
We investigate the use of a liquid metal ion gun (LMIG) combined with multiphoton resonance ionization of sputtered atoms and/or molecules to acquire mass-selected images with submicrometer spatial resolution. Images from several model systems are presented including those of an In grid, and of patterned surfaces of benzo[a]pyrene and tryptophan thin films. Since postionization for these systems yields ionization efficiencies that are considerably higher than those achieved with secondary ion mass spectrometry (SIMS), spatial resolution of 2600 A for molecular species could be achieved while static conditions were maintained. Cooling of the sample to < 210 K was shown to be essential for molecular systems since the number of thermally evaporating molecules overwhelms the number of sputtered molecules at room temperature. Other details necessary to incorporate laser postionization into a time-of-flight SIMS instrument using a pulsed LMIG source are also discussed.
我们研究了将液态金属离子枪（LMIG）与溅射原子和/或分子的多光子共振电离相结合，以获取具有亚微米空间分辨率的质量选择图像。展示了来自几个模型系统的图像，包括铟网格以及苯并[a]芘和色氨酸薄膜图案表面的图像。由于这些系统的后电离产生的电离效率远高于二次离子质谱（SIMS）所达到的效率，因此在保持静态条件的同时，可以实现分子物种2600埃的空间分辨率。对于分子系统，将样品冷却至<210 K被证明是必不可少的，因为在室温下热蒸发分子的数量超过了溅射分子的数量。还讨论了将激光后电离纳入使用脉冲LMIG源的飞行时间SIMS仪器所需的其他细节。
