The so-called nanoprobe, developed by the Department of Energy's Oak Ridge National Laboratory, uses an optical fiber tapered to a point measuring just 100 nanometers.

That tip then gets an extremely thin coating of nanoparticles of silver, which induces the surface-enhanced Raman scattering effect. Normally, when a sample is illuminated by a laser beam, there is a small reflection of light, known as Raman scattering. The light shows vibration energies, which are unique to each compound, and that information allows scientists to identify the substance.

With the Raman scattering nanoprobe, the laser light creates rapid oscillations of the electrons in the silver nanoparticles, which produce an enormous electromagnetic field that increases the Raman scattering signal.

"The significance of this work is that we are now able to perform direct analysis of samples -- even dry samples -- with no preparation of the surface," said Tuan Vo-Dinh, who leads the Oak Ridge team that developed the nanoprobe.

"Also, the small scale of the nanoprobe demonstrates the potential for detection in nanoscale environments, such as at the intracellular level."