Rangan Sylvie, Viereck Jonathan, Bartynski Robert A
Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, United States.
J Phys Chem B. 2020 Sep 10;124(36):7909-7917. doi: 10.1021/acs.jpcb.0c06423. Epub 2020 Aug 28.
The valence band spectra of three cyano-ionic liquids based on 1-ethyl-3-methylimidazolium (Im) paired with thiocyanate (SCN), dicyanamide (N(CN)), and tricyanomethanide (C(CN)) have been measured using ultraviolet and X-ray photoemission spectroscopy. Experimental spectra are compared to their corresponding density of states, weighted by photoemission cross sections, calculated for clusters of ions pairs of increasing size. Thus, this study bridges single ion approaches to 3D periodical DFT studies and enables the exploration of the different aspects of electronic structure establishment in ILs. Even for a relatively small cluster size, the relative energy of cation and anions states shifts by an amount that corresponds closely to that expected from the Madelung energy of a bulk IL, and the photoemission cross section-weighted DOS spectra are in good agreement with the measured valence bands. Trends in the relative energy and ionic character of the frontier orbitals across this series of cyano-ILs are discussed.
利用紫外光电子能谱和X射线光电子能谱测量了三种基于1-乙基-3-甲基咪唑鎓（Im）与硫氰酸盐（SCN）、双氰胺（N(CN)）和三氰甲烷化物（C(CN)）的氰基离子液体的价带光谱。将实验光谱与其相应的态密度进行比较，态密度由光电子发射截面加权，针对尺寸不断增加的离子对簇进行计算。因此，本研究搭建了从单离子方法到三维周期性密度泛函理论研究的桥梁，并能够探索离子液体中电子结构建立的不同方面。即使对于相对较小的簇尺寸，阳离子和阴离子态的相对能量移动量也与本体离子液体的马德隆能所预期的量密切对应，并且光电子发射截面加权的态密度光谱与测量的价带光谱吻合良好。讨论了该系列氰基离子液体前沿轨道相对能量和离子特性的趋势。
