Visualization of molecular soccer balls
Fullerenes are composed of 60 carbon atoms joined together in hexagonal rings to form a sphere that resembles a soccer ball. Fullerenes are of great interest to materials scientists because their interesting electronic properties make them attractive for use in advanced electronics and nanotechnology.
The electronic properties of fullerene can be modified by doping with other elements without altering its soccer-ball shape. In particular, salts of lithium ion-doped fullerene, which is denoted as Li+@C60, have been synthesized in high yield, and the structure of Li+@C60 has been determined. Li+@C60 salts have been used in solar cells and molecular switches with promising results.
To optimize the performance of Li+@C60 in applications such as photovoltaics and switching devices, it is important to thoroughly understand its electronic properties. An international research collaboration led by the University of Tsukuba recently expanded knowledge of Li+@C60 by imaging single Li+@C60 molecules via scanning tunneling microscopy (STM). STM can image materials with molecular-level resolution and provide information about the electronic structure of single molecules. The results were published in the journal Carbon.
âWe fabricated a thin-film sample suitable for STM by vacuum evaporation of a Li+@C60 salt on a copper substrate,â says study co-author Seiji Sakai. âOur subsequent microscopy examination revealed that although some lithium ions escaped during the evaporation process, the sample did contain some Li+@C60 molecules on the copper substrate.â
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