Dresden 2009 – wissenschaftliches Programm
DY 12.31: Poster
Dienstag, 24. März 2009, 14:30–16:30, P1A
Thermodynamic effects of an endohedral atom on the phase transition of fullerenes — •Adilah Hussien1, Andrey Lyalin2, and Andrey Solov’yov1 — 1Frankfurt Institute for Advanced Studies, Goethe University, Ruth-Moufang-Str. 1, Frankfurt am Main 60438, Germany — 2Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
Encapsulation of a species within a fullerene can be regarded as an impurity which modifies the thermodynamic properties of the fullerene cage. The magnitude of the induced change is dependent upon the interaction of the carbon atoms in the fullerene and the type of endohedral species. In this work, we demonstrate that an Argon encapsulated within C60 can be regarded as intrinsic pressure on the fullerene cage. This intrinsic pressure leads to a shift in the temperature required to fragment the fullerene cage, therefore affecting the phase transition behaviour of the fullerene from the cage structure to a gaseous state of carbon dimers. In this work, we construct a statistical mechanics model to explain this behaviour, as well as molecular dynamics simulations using the Tersoff potential. We demonstrate that the intrinsic pressure from the encapsulated species causes the fullerene system to be in one of its many isomer states. When the species is ejected out of the cage at high temperatures, the fullerene cage remains in the higher energy isomer state, therefore requiring less energy for a phase transition to its final gaseous phase of carbon dimers.