from the step-by-step dept.
A team of researchers in Japan have reported on a potentially useful phenomenon: reversible, light-induced nanometer-scale changes in the shape of a crystal. In a paper that appeared in the 2 March 2001 issue of Science, they report that irradiating the crystal with ultraviolet light induced the formation of regular, 1 nm size steps (the height of one molecular layer). The process could be reversed using light at another (visible) wavelength. The authors conclude:
ì The surface morphological changes can be explained by the molecular structural changes of diarylethenes regularly packed in the single crystal. These crystals could potentially be used as photodriven nanometer-scale actuators.î
Read more for the full abstract and citation in Science. Online access to the full paper requires a subscription to the journal. Note: Online access to the full paper requires a subscription to the journal.
Reversible Surface Morphology Changes of a Photochromic Diarylethene Single Crystal by Photoirradiation
Masahiro Irie Seiya Kobatake, Masashi Horichi
Science, 2 March 2001; 291:1769-1772.
The surface morphology of a diarylethene single crystal [1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene] determined by atomic force microscopy changed reversibly upon photoirradiation. The crystal underwent a thermally irreversible but photochemically reversible color change (colorless to blue) upon alternate irradiation with ultraviolet (wavelength = 366 nm) and visible (>500 nm) light that drove reversible photocyclization reactions. Upon irradiation with 366-nm light, new steps appeared on the (100) single-crystalline surface that disappeared upon irradiation with visible light (>500 nm). The step height, about 1 nm, corresponds to one molecular layer. Irradiation with 366-nm light formed valleys on the (010) surface that also disappeared by bleaching upon irradiation with visible light (>500 nm). The surface morphological changes can be explained by the molecular structural changes of diarylethenes regularly packed in the single crystal. These crystals could potentially be used as photodriven nanometer-scale actuators.
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, and CREST, Japan Science and Technology Corporation, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
