Acquisition of a Normal Incidence Electron Gun for the ASU SIMS

9615982 Hervig这笔赠款提供了95,210美元，作为为亚利桑那州Cameca 3f二次离子质谱仪(SIMS)购买正入射电子枪(NIEG)的部分费用。该附件补偿了在被碱金属(即Cs)正电离子束溅射的样品表面上发生的电荷积聚，碱金属(如Cs)是分析氧同位素和其他电负性元素(即H、C、F、Cl、P、S、As、Sb、Se)所必需的。这种电子枪的束法几何形状允许对使用内部设计的斜角电子枪进行的强烈电子轰击容易损坏的样品进行分析。该附件的添加将允许提高绝缘子相的氧同位素SIMS分析的精度(约为每毫升1)，并可能提高横向分辨率，因此将使其当前配置的SIMS的精度提高近1/2。由于增加了一支正入射电子枪，精度的提高无疑将被这位PI用于继续研究自生粘土矿物的早期成岩作用、基于火山岩中熔体包裹体的硫同位素分析的岩浆中挥发性元素收支以及环境样品中挥发性微量元素丰度的填图。***

9615982 Hervig This grant provides $95,210 as partial support of the costs of acquiring a normal incidence electron gun (NIEG)for the Cameca 3f secondary ion mass spectrometer (SIMS) at Arizona State. This accessory compensates for charge buildup that occurs on the surface of samples that are being sputtered with positively charged ion beams of alkali metals (i.e. Cs+), such as is necessary to analyze for oxygen isotopes and other electronegative elements (i.e., H, C, F, Cl, P, S, As, Sb, Se). The beam-normal geometry of this electron gun allows for analysis of samples that are prone to damage from intense electron bombardment that occurs using an oblique angle electron gun that was designed in-house. Addition of this accessory will allow an increase in the precision (to ca. 1 per mil)and perhaps in the lateral resolution of oxygen isotopic SIMS analyses of insulator phases and thus will provide for nearly a factor of two increase in the precision of their currently configured SIMS. The increase in precision affordable with the addition of a normal incidence electron gun will undoubtedly be used fruitfully by this PI in his continued studies of the early diagenesis of authigenic clay minerals, volatile element budgets in magmas based on Sulfur isotopic analyses of melt inclusions in volcanic rocks and mapping of volatile trace element abundances in environmental samples. ***