Scanning-induced structure transformation between self-assembled phases of pentacene on Ag/Si(1 1 1)

Using variable temperature scanning tunneling microscopy, we investigated the structure transformation of pentacene molecules on the Ag/Si(111)-(3×3)R30° substrate. It is demonstrated that the self-assembled brick-wall phase can be converted to another ordered chain-like phase with higher packing density in a large area (μm) by tip scanning at room temperature. Moreover, we show by temperature dependent experiments that the increment of the pentacene molecules during the transformation is supplied by a two-dimensional gas reservoir that exists on the surface of the saturated brick-wall phase at room temperature.