SAS President-Elect

Spectroscopy Europe’s Article Editor, John Chalmers, has recently been voted President-Elect 2007 of the Society for Applied Spectroscopy. Congratulations, John! He will be the first non-American resident to hold the post.

Single molecule detection

Researchers at ETH Zurich have developed a new high-resolution analytical procedure using tip-enhanced Raman spectroscopy, which has enabled them to localise and determine the chemical nature of individual molecules on a surface.

The sample is deposited on a gold surface, and a silver tip, roughly the size used in a scanning tunneling microscope is moved over the sample. Between the tip and the gold substrate, over an area of approximately 10×10nm, a strong electrical field is generated that amplifies the Raman signal by a factor of 10⁷.

By performing measurements on two different substances, they were able to show that, in principle, all compounds may be determined by this method. They are also sure that they can detect individual molecules by this procedure. For example, if the sample substance on the gold surface is more dilute, signals of the same intensity as before are measured, but at fewer locations where molecules are still present. The precision of the procedure is also demonstrated by the fact that the signals measured fluctuate when observed over a period of a few seconds. The researchers consider this to arise from molecular motion. If the Raman signals were to originate from a cluster of molecules, one would not expect such fluctuation.

This work was published in J. Phys. Chem., doi: 10.1021/jp064740r

Pittcon 2007

This year’s Pittcon takes place in Chicago, IL, USA, from 25 February to 2 March. Over 1000 companies are exhibiting this year. There are a number of innovations this year, including specialised groupings of exhibitors in Life Science and LIMS, and the incorporation of the posters onto the exhibit floor. As always, there is an extensive conference programme.