- 2018-01-15-and used a technique called electroless etching to make a wide range of nanowires. They "decorated" these wires with with variable and controlled densities, which increased the nanowires' surface area.
"Optimizing these vertically aligned structures took a lot of time in the beginning," said Nageswara Rao, another of the paper's authors. "We increased the surface area and to do this we needed to change the aspect ratio."
After optimizing their system to detect Rhodamine dye on a nanomolar level, these new substrates the team built enhanced Raman sensitivity by a factor of 10,000 to 100,000. The substrates detected concentrations of cytosine, a nucleotide found in DNA, and ammonium perchlorate, a molecule with potential for detecting explosives, in as dilute concentrations as 50 and 10 micromolar, respectively.
The results have given the team reason to believe that it might soon be possible to detect compounds in concentrations on the scale of nanomolar or even picomolar, Nageswara Rao said. The team's work has opened several avenues for future research, from experimenting with different nanoparticles such as gold, increasing the sharpness of the nanowires or testing these devices across several types of molecules.
雷同的研究结果早在2005年利用纳米氧化硅载体来增强红外光谱的探测能力（Journal of Applied Physics 98, 114310 (2005); ）（Applied Surface Science，, 15 December 2005, Pages 1197-1201）其探测能力提高1000倍。
More information: V. S. Vendamani et al, Three-dimensional hybrid silicon nanostructures for surface enhanced Raman spectroscopy based molecular detection, Journal of Applied Physics (2018).