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对电子材料中的微量元素进行表征。该奖项是为了表彰这种使用加速器质谱法（AMS）对电子材料进行稳定微量元素分析的仪器的开发。虽然AMS已应用于具有极高灵敏度的放射性同位素测定，但现有的AMS仪器不是为稳定元素分析而设计的，如果不进行大量修改，就无法充分执行这些测量。我们提出了一种具有超低样品污染的特高压溅射离子源的仪器，它将样品中经质量分析的负二次离子注入3 MV串联加速器中。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/电荷判别，其次是速度和总能量检测，提供了明确的元素识别，灵敏度为万亿分之一。该仪器将提供一种超灵敏的痕量分析技术，适用于各种各样的样品。

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.