Single-molecule detection with enhanced Raman scattering of tungsten oxide nanostructure

We have found that tungsten oxide nanorods have a very large enhancement effect on Raman scattering. The nanorods with adsorbed ¹²CO and ¹³CO at the ratio of 1 : 1 were dispersed on a Si substrate and Raman mapping was performed. The Raman images of ¹²CO and ¹³CO were completely different, indicating that a very small number of molecules at the single-molecule level were observed. We also confirmed the characteristic blinking phenomenon when single-molecule detection was performed. The very large enhancement effect of Raman scattering can be attributed to the {001}CS structure of the tungsten oxide nanorods. It was confirmed from the DFT calculation results that the {001}CS structure exhibits two-dimensional electrical conduction properties.