See Atoms in Motion!

Extract

It is impressive enough that individual atoms can be resolved with the atomic force microscope (AFM), but who would have thought that atomic motion would be detected so soon? Atomic resolution with the AFM was only recently achieved. As reported in this column, Franz Giessibl was able to demonstrate local resolution of adatoms of the Si(111) 7×7 reconstructed surface. Now, Yasuhiro Sugawara. Masahiro Ohta, Hitoshi Ueyama, and Seizo Morita of Hiroshima University have demonstrated atomic resolution of the surface of InP(110). Not only that, but images taken about one minute apart show that some of the atoms had moved! Sugawara et al, used a very compact AFM under ultrahigh vacuum (4 X 10^-8 Pa) to accomplish this impressive feat. A stiff (spring constant of 34 N/m) silicon cantilever was used. This stiffness, along with a mechanical resonant frequency of 151 kHz, was used to keep the cantilever from jumping onto the sample and crushing the initially sharp tip.