Manipulating molecules
Scientists at Free University in Berlin have for the first time manipulated single molecules using a scanning tunnelling microscope (STM). STMs are instruments used to study the structure of materials. In the experiment, researchers started with several iodabenzene molecules on a copper substrate. Then using the tip of the STM probe, they injected electrons into the iodabenzene to dissociate it into iodine and phenyl. The iodine atoms are moved away from the STM tip, leaving only the phenyl. Next, the tip pulls one phenyl close to another; they are not yet chemically bonded, though: pulling on one phenyl does not bring the other one along. Finally, another splash of electrons from the tip effectively welds the two phenyls together. This technique could be used to engineer new molecules by selective replacement ( Physical Review Letters, September 25, 2000).