GOLD DUST EXTENDS RAMAN’S REACH

Abstract

A SPRINKLING OF GOLD nanoparticles coated with a thin oxide shell allows surface-enhanced Raman scattering (SERS) to probe a wider variety of samples, including those with irregular morphology. SERS usually involves placing a sample on a roughened metal surface, which amplifies the Raman signal from the sample. Zhong Qun Tian of Xiamen University, in China; Zhong Lin Wang of Georgia Tech; and coworkers turn this usual configuration upside down. The researchers sprinkle the sample with silica-or alumina-coated gold nanoparticles and then collect Raman spectra ( Nature 2010, 464, 392). They call their new method shell-isolated nanoparticle-enhanced Raman spectroscopy, or SHINERS. The “smart dust” consists of 55-nm gold nanoparticles encased in a shell of silica or alumina. The shell, which is about 2 nm thick, isolates the particles from the sample and from each other but still allows enhancement of the Raman signal. “Each particle is like an independent probe, but the layer is ...