Nonthermal decomposition of C60 polymers induced by tunneling electron injection

Scanning tunneling microscopic (STM) studies of C-60 films deposited on highly oriented pyrolytic graphite substrates revealed that the electron injection from the STM tip induces the decomposition (isomerization) of the C-60 molecules that have been polymerized also by the electron injection into the films. Both reaction rates were characterized by a linear dependence on the injected tunneling current and a common threshold around 2 V in the sample bias dependence. We discuss two nonthermal mechanisms for the polymerization and decomposition reactions: electronic excitation mechanism by Auger decay and a hypothetical ionic reaction model. (C) 2004 American Institute of Physics.