Nucleation and Growth of the Prototype Azabenzene 1,3,5-Triazine on Graphite Surfaces at Low Temperatures

作者：Martinez Galera Antonio J^*; Gomez Rodriguez Jose M

来源：Journal of Physical Chemistry C, 2011, 115(22): 11089-11094.

DOI：10.1021/jp200613c

We report on research performed by using scanning tunneling microscopy (STM) during the first stages of nucleation and growth of a prototype azabenzene, 1,3,5-triazine, on highly oriented pyrolitic graphite (HOPG) surfaces at low temperatures under ultrahigh vacuum conditions. This work reveals the formation at temperatures below 100 K of two-dimensional fractal shape islands of 1,3,5-triazine where the molecules are ordered in an hexagonal lattice. By using nucleation theory on well-controlled experiments, where sample temperature and deposition rate were alternatively changed, we have extracted important parameters such as the critical nucleus size (equal to one) and the energy barrier for single molecule diffusion (E(d) = 55 +/- 8 meV). This energy barrier, though low enough to be considered the result of a weak molecule substrate interaction corresponding to a physisorption process, is much higher than the one obtained very recently for the benzene graphite system [Hedgeland, H.; et al. Nat. Phys. 2009, 5, 561]. This comparison suggests that the presence of the nitrogen atoms on the heterocycle of azabenzenes can lead to a substantial gain on the bonding energy with respect to pure benzenic systems.

• 出版日期2011-6-9