ABSTRACT
Methods for the manipulation of nanometer-scale objects can be grouped into two philosophies [1]: selfassembly of molecular components, a process widely seen in nature, is described as the ‘‘bottom-up approach” (small things make larger things); the opposite is the ‘‘top-down approach,” where large machines (such as the tools of modern semiconductor manufacture) are used to make much smaller products. While the former is considered to be ultimately preferable, modern technology has only been able to manipulate molecular-scale objects at will using the top-down approach, such as writing using xenon atoms as ink and a scanning tunneling microscope as a pen [2].
