Being able to detect a Raman signal from a single molecule illuminated with laser light has exciting applications in new materials research and analytical chemistry. However, the team that developed the technique is also using it to find out more about the molecules themselves.
Improving the sensitivity of the detecting technique is a key issue because Raman signals are very weak. Surface-enhanced Raman spectroscopy (SERS) offers a million-fold improvement in sensitivity over standard Raman spectroscopy. In 2006, the group developed a reliable method to study the conditions under which single molecule detection is possible with SERS, thereby effectively ending a debate that has been going on for some years.
“We have chosen to focus our thinking and research on developing the ideas and basic understanding around the method itself, rather than pushing into resource-hungry applications of the technique. It’s nice to see that other people are now doing that, based on what we have achieved,” says Eric Le Ru, the younger half of the Etchegoin/Le Ru ‘dynamic duo’.
The success of this approach is borne out not only by the tally of 50–60 papers published by the group since 2006 but also by the fact that one of Etchegoin’s and Le Ru’s papers is currently the most cited research article in the Journal of Physical Chemistry C.
Not all their samples are high-tech new materials. Eric recently worked on a manuscript from the Alexander Turnbull Library to identify a particular pigment that had been used. “Some of these pigments have very characteristic Raman signals, so we were able to put it under the laser and have a look, without damaging the original work. From that you can piece together information about when and where it may have been created.
“Our team is really lively and interactive. New ideas come from our discussions every day and we just run with the most exciting ones.”