The behavior of tetradecane and octadecanol adsorbed on graphite in solid-gas interface is investigated at room temperature by STM. The studies reveal that tetradecane and octadecanol on graphite are self-assembled into a high degree of two-dimensional order, and the lamellar structure, which is similar to that of STM observation in solid-liquid interface, is obtained. But the high-resolution images give striking differences in molecular arrangement, lattice constant and orientation of molecules in one lamella, and we attribute these differences to the solvent effect suggested in previous neutron diffraction studies.