Credit: © 2007 AAAS

Diamonds have many useful industrial properties, in addition to their better-known role as a 'girl's best friend'. Now researchers in the US, Germany and Ukraine have shown that tiny carbon-based molecules known as diamondoids may also be useful for applications1. The team has shown that diamondoid monolayers can emit electrons with well-defined energies when excited by photons.

Diamondoids exist in a number of different cage-like structures, with the simplest of these — adamantane — made of 10 carbon and 16 hydrogen atoms. In the latest work, Wanli Yang of Stanford University and the Lawrence Berkeley National Laboratory and co-workers worked with a higher form of diamondoid known as tetramantane (C22H28). They deposited monolayers of tetramantane that had been functionalized with thiol groups onto gold and silver surfaces and illuminated them with X-rays. For the silver samples, some 68% of the electrons were emitted with energies of around 1 electron volt.

Diamondoids have not yet been synthesized in the laboratory, so most of the experiments to date have been performed on samples extracted from petroleum by researchers at the Chevron oil company. The monolayers could prove useful for applications such as electron microscopy, electron-beam lithography and field-emission flat-panel displays.