Development of an Accelerator Mass Spectrometry Facility forTrace Impurity Characterization of Electronic Materials

目前需要在十亿分之一的杂质水平上表征电子材料中的痕量元素。该奖项是为了表彰使用加速器质谱仪(AMS)对电子材料进行稳定的微量元素分析的仪器的开发。虽然AMS已被应用于具有极高灵敏度的放射性同位素测定，但现有的AMS仪器不是为稳定的元素分析而设计的，如果没有广泛的改进，就不能充分地进行这些测量。我们提出了一种超低样品污染超高压溅射离子源的仪器，它将样品中经过质量分析的负次离子注入3 MV串列加速器。在串联加速过程中，电子从离子中剥离；对于大于2+的电荷态，只有原子离子存活。动量/电荷和能量/电荷识别，然后是速度和总能量检测，提供了灵敏度为万亿分之一的明确的元素识别。该仪器将提供一种适用于多种样品的超灵敏痕量分析技术。

There is a present need to characterize trace elements in electronic materials at impurity levels of sub parts-per-billion. This award is for the development of such an instrument for stable trace element analysis of electronic materials using Accelerator Mass Spectrometry (AMS). While AMS has been applied to radioisotope determinations with extremely high sensitivities, existing AMS instruments are not designed for stable element analysis and can not adequately perform these measurements without extensive modifications. We propose an instrument with an ultra-low sample-contamination UHV sputter ion source which injects mass-analyzed negative secondary ions from the sample into a 3 MV tandem accelerator. During tandem acceleration, electrons are stripped from the ions; for charge states greater than 2+, only atomic ions survive. Momentum/charge and energy/charge discrimination, followed by velocity and total energy detection, provide unambiguous elemental identification with a sensitivity of 1 part-per-trillion. The proposed instrument will provide a super-sensitive trace analysis technique which is applicable to a large variety of samples.