Analysis of nano-quantities of geo-materials by Total-Reflectance X-Ray Fluorescence

地球科学研究的规模越来越小，或者是出于必要，例如在模拟地球中的高压高温域时，压力与实验样本大小成反比，或者是出于设计，例如以越来越精细的时间分辨率询问地质记录。这一趋势产生了重大的分析挑战，需要以更小的样品数量量化完整的周期表。这里要求的全反射X射线荧光光谱仪（TXRF）非常适合解决这些问题。TXRF使用掠射角（0.1°）初级X射线束在蒸发流体、悬浮固体或岩石晶片的薄膜中产生次级荧光X射线。薄膜掠射角配置消除了元素干扰和基质效应，并允许检测器安装在非常靠近样品的位置，以优化计数率。因此，TXRF的特点是背景非常低，可以检测到低至ppb级的元素。此外，它是非破坏性的，可以分析大多数周期表，并可以同时处理从质量%到ppb的浓度范围。 TXRF仪器将使共同申请人进行的各种研究项目，包括他们的发现补助金研究计划。它将允许对实验中合成的少量液体和固体进行主要和微量元素分析。这项实验研究的目的是开发工具，从沉淀的矿物中重建流体的成分，并限制金属在含水流体中的稳定性，以进行矿流体演化的热力学建模。在不进行任何稀释或其他样品预处理的情况下分析复杂流体和盐水的能力将用于研究，以确定海洋沉积物和海水之间的元素循环，并确定沉积物是这些元素的净汇还是净源。它还将用于了解印度尼西亚Kawah Ijen火山释放的酸性金属盐水对环境的影响，并探索冰岛地热流体中金属的流动性。带状晶体和层状变质沉积物的研究受益于TXRF提高的采样分辨率，这使得岩浆系统和沉积盆地的演化，分别在更精细的时间尺度进行调查。这项研究极大地增强了我们对元素循环和人类对这些的影响的理解，它允许重建过去的环境，并将其用作气候变化前瞻性建模的代理，并将提供对矿石形成的见解，所有这些都解决了与污染，气候变化和自然资源减少有关的未来的关键社会不确定性。

Geoscience research takes place at progressively smaller scales, either out of necessity, for example in the simulation of high-pressure high-temperature domains in the Earth where pressure inversely scales with experiment sample size, or by design, for example to interrogate the geological record at increasingly finer time-resolution. This trend produces significant analytical challenges related to the need to quantify the complete periodic table in ever smaller sample quantities. The Total Reflectance X-Ray Fluorescence Spectrometer (TXRF) requested here is ideally suited to overcome these issues. TXRF uses a grazing angle (0.1°) primary X-Ray beam to generate secondary fluorescence X-rays in a thin film of evaporated fluid, suspended solid or rock wafer. The thin-film grazing-angle configuration eliminates element interferences and matrix effects, and allows the detector to be mounted very close to the sample to optimize count rates. As a result, TXRF is characterized by very low backgrounds and can detect elements down to ppb-levels. Moreover, it is non-destructive, can analyse most of the periodic table, and can handle concentrations ranging from mass % to ppb simultaneously. The TXRF instrument will enable a wide diversity of research projects conducted by the co-applicants, including their Discovery Grant research programs. It will allow for the small quantities of fluids and solids synthesized in experiments to be analysed for major and trace elements. This experimental research aims to develop tools to reconstruct the compositions of fluids from the minerals that precipitated from them, and constrain the stability of metals in aqueous fluids to allow for thermodynamic modelling of ore-fluid evolution. The ability to analyse complex fluids and brines without any dilution or other sample pre-processing will be used in studies to determine the cycling of elements between marine sediments and seawater, and to determine whether the sediment acts as a net sink or source of these elements. It will also be applied to understand the environmental impact of acidic metal-laden brines released by Kawah Ijen volcano in Indonesia and to explore the mobility of metals in geothermal fluids in Iceland. Studies of zoned crystals and bedded meta-sediments benefit from the improved sampling resolution enabled by TXRF, which allows for the evolution of magmatic systems and sedimentary basins, respectively, to be investigated at much finer temporal scales. This research greatly enhances our understanding of element cycles and human's impact on these, it allows for past environments to be reconstructed and used as a proxy in forward modelling of climate change, and will provide insights into ore formation, all of which address key societal uncertainties for the future related to pollution, climate change and dwindling natural resources.