Goldberger David, Evlyukhin Egor, Cifligu Petrika, Wang Yonggang, Pravica Michael
High-Pressure Science and Engineering Center (HiPSEC) and Department of Physics, University of Nevada Las Vegas (UNLV) , Las Vegas, Nevada 89154-4002, United States.
HPCAT, Geophysical Laboratory, Carnegie Institution of Washington , 9700 South Cass Avenue, Argonne, Illinois 60437, United States.
J Phys Chem A. 2017 Sep 28;121(38):7108-7113. doi: 10.1021/acs.jpca.7b05604. Epub 2017 Sep 18.
We report measurements of the X-ray-induced decomposition of crystalline strontium oxalate (SrCO) as a function of energy and high pressure in two separate experiments. SrCO at ambient conditions was irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 28 keV. A broad resonance of the decomposition yield was observed with a clear maximum when irradiating with ∼20 keV X-rays and ambient pressure. Little or no decomposition was observed at 15 keV, which is below the Sr K-shell energy of 16.12 keV, suggesting that excitation of core electrons may play an important role in the destabilization of the CO anion. A second experiment was performed to investigate the high-pressure dependence of the X-ray-induced decomposition of strontium oxalate at fixed energy. SrCO was compressed in a diamond anvil cell (DAC) in the pressure range from 0 to 7.6 GPa with 1 GPa increments and irradiated in situ with 20 keV X-rays. A marked pressure dependence of the decomposition yield of SrCO was observed with a decomposition yield maximum at around 1 GPa, suggesting that different crystal structures of the material play an important role in the decomposition process. This may be due in part to a phase transition observed near this pressure.
我们在两个独立实验中报告了作为能量和高压函数的X射线诱导的草酸锶晶体（SrCO）分解的测量结果。在环境条件下，用能量范围为15至28keV的单色同步加速器X射线照射SrCO。在用约20keV X射线和环境压力照射时，观察到分解产率有一个宽的共振，且有一个明显的最大值。在15keV时几乎没有观察到分解，该能量低于Sr K壳层能量16.12keV，这表明内层电子的激发可能在CO阴离子的去稳定化中起重要作用。进行了第二个实验，以研究在固定能量下X射线诱导的草酸锶分解对高压的依赖性。在金刚石对顶砧室（DAC）中将SrCO在0至7.6GPa的压力范围内以1GPa的增量进行压缩，并用20keV X射线进行原位照射。观察到SrCO分解产率对压力有明显依赖性，在约1GPa处分解产率最大，这表明材料的不同晶体结构在分解过程中起重要作用。这可能部分归因于在该压力附近观察到的相变。
