太赫兹光谱学研究CL-20/MTNP共晶振动特性  

Research on vibrational features of CL-20/MTNP cocrystal by terahertz spectroscopy

作　　者：刘泉澄 杨富 张祺[2] 段勇威 邓琥[3] 尚丽平[1] Liu Quan-Cheng;Yang Fu;Zhang Qi;Duan Yong-Wei;Deng Hu;Shang Li-Ping(School of Information Engineering,Southwest University of Science and Technology,Mianyang 621000,China;Institute of Chemical Materials,China Academy of Engineering Physics,Mianyang 621050,China;Tianfu Institute of Research and Innovation,Southwest University of Science and Technology,Chengdu 610299,China)

机构地区：[1]西南科技大学信息工程学院,绵阳621000 [2]中国工程物理研究院化工材料研究所,绵阳621050 [3]西南科技大学四川天府新区创新研究院,成都610299

出　　处：《物理学报》2024年第19期212-218,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:22305198);西南科技大学博士基金(批准号:21ZX7143)资助的课题。

摘　　要：共晶是一种分子层次调控材料物化性质的高效方法,然而目前共晶复杂体系结构与宏观性质间关系一直难以得到深入理解.本文依据太赫兹光谱可激发晶体内弱作用的优势,以CL-20/MTNP共晶为对象开展了太赫兹振动光谱研究.首先,测量CL-20、MTNP和共晶CL-20/MTNP的太赫兹吸收光谱.其次,分析了基于密度泛函理论的振动计算方法,获得了3种物质太赫兹频段振动特性,对吸收光谱进行振动匹配.最后,采用振动分解方法将晶体分子的整体振动分解为分子间和分子内振动.在此基础上,分析了共晶前后振动变化规律.结果表明:共晶后新形成的弱相互作用由CL-20分子主导,同时MTNP分子主要通过3个硝基与CL-20分子交互作用.本文的研究结论为共晶热性质提供了微观解析.Cocrystals represent an effective method to manipulate the physicochemical properties of materials at a molecular level.However,understanding the relationship between their complex crystal structures and macroscopic properties is a challenge.In this paper,by using terahertz(THz)spectroscopy to characterize noncovalent interactions within crystals,the THz vibrational spectra of the CL-20/MTNP cocrystal are studied.Firstly,the THz spectra of CL-20,MTNP,and the CL-20/MTNP cocrystal are measured at room temperature.Both absorption positions and intensities of the cocrystals differ from those of their original components,confirming the unique advantage of terahertz spectroscopy in cocrystal identification.Secondly,the THz vibrational features of the three materials are calculated based on density functional theory(DFT).Then,the experimental absorptions are matched with the calculated vibrations.Furthermore,a vibrational decomposition method is employed to decompose the molecular vibrations into intermolecular and intramolecular vibrations.The vibrational variations of the cocrystal compared with its original components are analyzed.The results reveal that in the cocrystal,the intermolecular vibrational modes of both CL-20 and MTNP molecules have changed compared with their raw materials.This indicates that the non-covalent interactions in the cocrystal have changed the original intermolecular interactions of these molecules.Consequently,this enhancement promotes the heat transfer between MTNP and CL-20 molecules,thereby improving the thermal stability of the cocrystal.These findings in this study demonstrate that the THz vibrational spectroscopy technology helps establish a relationship between the molecular structure of cocrystal and its macroscopic properties.This research contributes to deepening our understanding of cocrystal systems and opens up a new way for designing and optimizing materials.

关 键 词：太赫兹光谱 密度泛函理论 振动分解 CL-20共晶 

分 类 号：O73[理学—晶体学] O441.4