How To Make Buckyballs In Space
Fullerenes are very large carbon molecules, such as C60 and C70. It has been difficult to understand how such large, complicated molecules can form in space. Recently, a group of UArizona scientists (J. J. Bernal, P. Haenecour, T. J. Zega, and L. M. Ziurys) in Astronomy, Arizona Radio Observatory, Chemistry and Biochemistry, Planetary Sciences, Materials Science and Engineering, and their colleagues, published laboratory research and meteorite research that provides a mechanism for making this complicated molecule in space. Nature Magazine also published a "News & Views" article on this work. We are pleased that Regents' Professor Lucy Ziurys (Astronomy Dept, and Dept of Chemistry and Biochemistry) and her colleagues have given us a summary of the work:
"The recent detection of the fullerene molecules C60 and C70 in the planetary nebula Tc 1 and other interstellar and circumstellar sources has revolutionized our notion of the chemical complexity in space. The formation of these very complex molecules, by interstellar standards has been difficult to explain in the hydrogen-rich environment of interstellar space, given that they are composed of pure carbon. Our paper puts forth a new, facile mechanism for formation of interstellar C60 based on new laboratory results. Our work suggests that C60 and other fullerenes are produced from the shock heating of silicon carbide (SiC) grains, commonly formed in circumstellar envelopes of evolved stars. Using transmission electron microscopy (TEM), analog SiC grains were heated and bombarded with high energy ions, mimicking the environment in circumstellar envelopes. TEM images showed that silicon was leached from the grain surface, leaving layers of graphite behind. Where surface defects were present, spherical and hemispherical carbon nanobuds appeared with the diameter of C60. Furthermore, our analysis of a presolar grain extracted from a meteorite revealed a silicon carbide center surrounded by graphite, consistent with our lab experiments. These results demonstrate that fullerenes can be readily formed from SiC grains in ejecta from evolves stars and subsequently delivered into the ISM. "
