Nucleation growth of a platinum porphyrin derivative adsorbed on a Cu (100) surface was observed with a scanning tunneling microscope. The molecule attached with four di-tert-butylphenyl groups allowed equilibrium between diffusional gas phase and two-dimensional nuclei. To minimize the free energy for nucleation, the registry of the molecules into the kink sites resulted in formation of nuclei with singular, rectangular contours. Dependence of the equilibrium conditions on the sample-tip bias voltages was also presented.

DOI: 10.1021/nl0255597