Raman X-ray spectroscopy of photo-dissociation of standard alcohol medium for high pressure experiments under x-ray irradiation

The intense x-rays available at EBS-ESRF are known to be able to trigger undesired effects, such as chemical modifications in radiation sensitive materials. Recently, we have observed the chemical dissociation of the alcohol solution used as pressure transmitting medium in high-pressure experiments. The reaction is complex, involving the production of liquid hydrogen and solidification of solids of unknown stoichiometry. To determine the nature of the different products of this speciation as a function of pressure, we propose to perform X-Ray Raman Spectroscopy in-situ within Diamond Anvil Cell, as this is the only technic allowing us to probe the absorption edges of low-z elements under pressure. A successful experiment will lead to the determination of the nature of the modified pressure transmitting elements as a function of dose and pressure, providing a comprehensive base for the high-pressure community to design experiments and avoid undesired sample-environment interactions.

众所周知，EBS-ESRF（欧洲同步辐射光源增强亮度光源，Enhanced Brilliance Source at European Synchrotron Radiation Facility）产生的高强度X射线可诱发辐射敏感材料发生化学改性等不良效应。近期，我们在高压实验中观察到用作传压介质（pressure transmitting medium）的醇类溶液发生了化学解离。该反应过程较为复杂，会生成液态氢，并形成化学计量比（stoichiometry）未知的固态产物。为明确该化学解离过程中不同产物的性质随压力的变化规律，我们计划在金刚石对顶砧（Diamond Anvil Cell, DAC）内开展原位X射线拉曼光谱（X-Ray Raman Spectroscopy）实验——这是目前唯一可在高压环境下探测低Z元素（low-Z elements）吸收边的技术手段。若实验取得成功，我们将明确改性后的传压介质组分随辐照剂量与压力的变化规律，可为高压领域科研人员设计实验、规避有害的样品-环境相互作用提供坚实的研究基础。