Acquisition of a Normal Incidence Electron Gun for the ASU SIMS

Hervig这笔拨款提供了95,210美元，作为为亚利桑那州Cameca 3f次级离子质谱仪（SIMS）购买正常入射电子枪（NIEG）的部分费用支持。该附件补偿了在样品表面发生的电荷积聚，这些样品被带正电荷的碱金属离子束（即Cs+）溅射，例如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。该电子枪的光束法向几何形状允许分析容易受到强烈电子轰击损坏的样品，使用内部设计的斜角电子枪。该附件的添加将允许提高精度（约1 / mil），并且可能在绝缘体相的氧同位素SIMS分析的横向分辨率中，从而将其当前配置的SIMS的精度提高近两倍。随着普通电子枪的加入，精度的提高无疑将被这位PI用于他的后续研究中，包括自生粘土矿物的早期成岩作用，火山岩熔体包裹体硫同位素分析的岩浆中挥发性元素预算，以及环境样品中挥发性微量元素丰度的绘制。＊＊＊

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. ***