Two-dimensional crystal growth process of n-alkane molecules observed using scanning tunneling microscope

The growth stages of two-dimensional crystal in an n-alkane molecule (nC₃₃ H₆₈) were investigated using a scanning tunneling microscope (STM) for the samples vacuum-deposited on a graphite substrate. The STM image revealed that the nuclei with a diameter of about 2 nm, which is coincident with the value estimated for the molecules with random conformation, arrange hexagonally in the initial growth stage. It is suggested that further growth was promoted by the increase in the density of the molecules adsorbed on the substrate as well as by their thermal and diffusible motions. Moreover, the mutual relationship between n-alkane molecules and the graphite lattice, namely an epitaxial effect, is discussed with respected to the atomic-resolution STM images.