Development of a High Ionization Efficiency Molten Glass Ion Emitter

该项目涉及对使用电化学技术来提高液态玻璃离子发射器的金属离子生产效率的评估。总体而言，该项目旨在使热电离质谱仪(TIMS)能够产生比目前对地质感兴趣的元素(如铅)更高精度的元素同位素比率测量。在这个项目中，我们将研究使用现代电化学技术来提高熔融玻璃离子发射器(又名“硅凝胶”离子发射器)的效率。分析化学界最近的研究为从液体玻璃中发射离子的过程提供了新的见解。这些研究表明，在质谱仪的工作条件下，硼硅酸盐玻璃熔体(包括铅和银)中的金属掺杂主要以中性金属原子的形式存在。这开启了一种可能性，即增加玻璃中金属离子的比例可能会导致更强的发射金属离子束。我们的工作将包括探索高真空下熔融玻璃的电化学性质，这是热电离质谱计所经历的条件。我们将使用为电化学实验和方波伏安法改装的真空室“试验台”来评估金属(铅、钼、铁、铜等)的氧化还原行为。掺杂在熔融的硼硅酸盐玻璃中。实验装置已经搭建完成，并且已经产生了熔融的硼硅酸盐玻璃的简单循环伏安图，证明了该方法的可行性。我们的实验将被用来确定在熔融玻璃中产生持续阳极电流所需的最佳电极电位，该阳极电流对应于金属掺杂的氧化。有了这些信息，我们将设计和建造一个可以用于我们现有的Finnigan-MAT 261 TIM的电化学池，并确定熔融玻璃中产生的阳极电流是否会导致这些玻璃对各种金属杂质的离子发射增加。如果成功，该项目将导致使用铀-铅技术对地质材料进行更高精度的年龄测定，并将对需要高精度元素同位素比率测定的其他学科产生影响，包括生物化学和核取证。大部分工作将作为博尔德科罗拉多大学地质科学系一名西班牙裔女性博士生论文研究的一部分进行。

This project involves an evaluation of the use of electrochemical techniques to improve the efficiency of metal ion production of liquid glass ion emitters. Overall, the project is designed to allow thermal ionization mass spectrometry (TIMS) to generate higher precision elemental isotope ratio measurements than is currently possible for elements of geologic interest (such as Pb). In this project we will investigate the use of modern electrochemical techniques to increase the efficiency of molten glass ion emitters (aka "Si gel" ion emitters). Recent studies from the analytical chemistry community have provided new insights into the processes of ion emission from liquid glasses. These studies have suggested that under the operating conditions in mass spectrometer, metal dopants in borosilicate glass melts (including Pb and Ag) are dominantly present as neutral metal atoms. This opens the possibility that increasing the proportion of metal ions in the glass could result in a more intense emitted metal ion beam. Our work will involve exploring the electrochemical properties of molten glasses under high vacuum, the conditions experienced in the source of a thermal ionization mass spectrometer. We will use a vacuum chamber "test bench" retrofitted for electrochemical experiments and square wave voltammetry to assess the oxidation-reduction behavior of metals (Pb, Mo, Fe, Cu, etc.) doped in molten borosilicate glasses. The experimental apparatus has already by constructed and simple cyclic voltammagrams of molten borosilicate glasses have already been generated, demonstrating the feasibility of our approach. Our experiments will be used to determine the optimal electrode potentials required to produce sustained anodic currents in the molten glasses, the anodic currents corresponding to oxidation of the metal dopants. Armed with this information we will design and construct an electrochemical cell that can be used in our existing Finnigan-MAT 261 TIMS and determine if the anodic currents generated in the molten glasses result in increased ion emission from these glasses for various metal dopants. If successful, this project should lead to higher precision age determinations for geologic materials, using U-Pb techniques, and will have implications to other disciplines requiring high precision elemental isotopic ratio determinations, including biochemistry and nuclear forensics. Most of the work will be carried out as part of the dissertation research of a female, Hispanic PhD student in the Department of Geological Sciences, University of Colorado, Boulder.