Structural Study of Endohedral Mtallaofullerenes encapsulated in peapod.

富勒烯笼中封装的金属原子的分子结构和键合性质是关系到金属富勒烯内嵌结构和金属富勒烯封装豆荚稳定性的重要结构信息。利用最大熵法 (MEM) 通过同步辐射 (SR) 粉末衍射对内嵌金属富勒烯进行了实验电荷密度研究。首次测定了内嵌金属富勒烯（Gd@C_<82>、La_2@C_<80>、Y_2@C_<82>、Y_2C_2@C_<84>）的结果。金属富勒烯的精确MEM电荷密度揭示了金属原子与碳笼之间离子和/或共价键的存在以及碳笼内金属原子的热运动特征。 MEM/Rietveld方法是确定富勒烯内嵌结构数据分析的关键方法，是为纳米多孔材料的强大结构分析技术而进一步发展的。

The molecular structure and bonding nature of metal atoms encapsulatd in fullerene cage is important structural information relating to stability of metallofullerene endohedral structure and the metallofullerene encapsulating peapods. The experimental charge density studies of endohedral metallofullerenes by the Synchrotron Radiation (SR) powder diffraction utilizing the Maximum Entropy Method (MEM) were carried out. Results of the endohedral metallofulleres (Gd@C_<82>, La_2@C_<80>, Y_2@C_<82> and Y_2C_2@C_<84>, ) were determined for the first time. The precise MEM charge densities of the metallofullerenes reveal existence of ionic and/or covalent bonding between metal atoms and carbon cage as well as the feature of thermal motion of metal atoms inside the carbon cage. The MEM/Rietveld method, which is the crucial methods for data analysis in order to determine endohedral structure of the fulleride, were further developed for the powerful structure analysis technique of nano-porous materials.