基于X射线荧光光谱的温稠密物质电子结构密度效应研究  

Density effect on electronic structure of warm dense matter based on X-ray fluorescence spectroscopy

作　　者：张志宇[1] 赵阳[1] 青波[1] 张继彦[1] 马建毅[2] 林成亮 杨国洪[1] 韦敏习[1] 熊刚[1] 吕敏 黄成武[1] 朱托[1] 宋天明[1] 赵妍[1] 张玉雪 张璐[1] 李丽灵[1] 杜华冰[1] 车兴森[1] 黎宇坤[1] 詹夏宇[1] 杨家敏[1] Zhang Zhi-Yu;Zhao Yang;Qing Bo;Zhang Ji-Yan;Ma Jian-Yi;Lin Cheng-Liang;Yang Guo-Hong;Wei Min-Xi;Xiong Gang;Lü Min;Huang Cheng-Wu;Zhu Tuo;Song Tian-Ming;Zhao Yan;Zhang Yu-Xue;Zhang Lu;Li Li-Ling;Du Hua-Bing;Che Xing-Sen;Li Yu-Kun;Zhan Xia-Yu;Yang Jia-Min(Laser Fusion Research Center,China Academy of Engineering Physics,Mianyang 621900,China;Institute of Atomic and Molecular Physics,Sichuan University,Chengdu 610065,China;Institute of Applied Physics and Computational Mathematics,Beijing 100088,China)

机构地区：[1]中国工程物理研究院激光聚变研究中心,绵阳621900 [2]四川大学原子与分子物理研究所,成都610065 [3]北京应用物理与计算数学研究所,北京100088

出　　处：《物理学报》2023年第24期189-195,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12004351,11734013)资助的课题。

摘　　要：受密度及温度等环境效应影响,温稠密物质的电子结构显著变化,其理论描述非常复杂,精密实验数据亦非常缺乏.本文通过发展主动探测的X射线荧光光谱方法,从实验上定量研究了密度效应对温稠密物质电子结构的影响,有助于深入理解温稠密物质的电子结构变化,并为相关理论模型提供实验验证.在万焦耳激光装置上,设计特殊构型黑腔加载约2倍固体密度、2 eV的Ti样品.利用激光辐照V产生的热发射线泵浦Ti的荧光,并采用高效高分辨的晶体谱仪诊断样品的X射线荧光光谱.实验结果显示,2倍固体密度Ti样品荧光谱线K_(β)与K_(α)的能量差(△EK_(β)-K_(α))相对于冷样品红移约2 eV.理论上采用两种方法进行计算并与实验结果比较,其中有限温度相对论密度泛函方法高估了密度效应对谱线移动的影响,而“two-step Hartree-Fock-Slater”方法低估了密度效应的影响.Warm dense matter(WDM),a kind of transition state of matter between cold condensed matter and high temperature plasma,is one of the main research objects of high energy density physics(HEDP).Compared with the structure of isolated atom,the electron structure of WDM will change significantly because of the influences of density and temperature effect.As WDM is always strongly coupled and partly degenerate,accurate theoretical description is very complicated and the accurate experimental research is also very challenging.In this paper,the density effect on the warm dense matter electron structure based on the X-ray fluorescence spectroscopy is studied.The warm dense titanium with density larger than solid density is produced experimentally based on a specially designed hohlraum.Then,the titanium is pumped to emit fluorescence by using the characteristic line spectrum emitted by the laser irradiating the pump material(Vanadium).The X-ray fluorescence spectra of titanium with different states are diagnosed by changing the delay time between the pump laser and drive laser.The experimental fluorescence spectrum indicates that the difference in energy K_(β)K_(α)∆EK_(β)-K_(α)between and()of the compressed titanium(7.2-9.2 g/cm3,1.6-2.4 eV)is about 2 eV smaller than that of cold titanium.Two theoretical methods,i.e.finite-temperature relativistic density functional theory(FTRDFT)and two-step Hartree-Fock-Slater(TSHFS),are used to calculate the fluorescence spectrum of∆EK_(β)-K_(α)warm dense titanium.The calculated results indicate that the energy difference()decreases with the increase of density but changes slowly with the increase of temperature during the calculated state(4.5-13.5 g/cm3,0.03-5 eV).The FTRDFT overestimates the density effect on the line shift,while TSHFS underestimates the density effect.The future work will focus on optimizing the experimental method of X-ray fluorescence spectroscopy,obtaining X-ray fluorescence spectrum of titanium with more states,and then testing the theoretical method fo

关 键 词：温稠密物质 电子结构 密度效应 X射线荧光光谱 

分 类 号：O522[理学—高压高温物理]