Optical image of a TERS tip with the
laser beam focused at the tip-end

TERS image of single wall carbon
nanotubes with spatial resolution
of ~30 nm

The Tip-Enhanced Raman Spectrometer (TERS) or NanoRaman instrument uses a specially prepared AFM tip [1], which is kept within a few nanometres of the sample surface. The sample is illuminated by a low power laser beam (~1 mW), which is focused using a far field objective lens. The scattered light is collected using the same objective lens in reflection mode [2], or another objective lens positioned on the other side of the sample in transmission mode [3]. High resolution imaging of single wall carbon nanotubes has demonstrated the increased spatial resolution, as shown above. We are investigating three aspects of TERS; (a) the factors affecting the TERS-enhancement factor, (b) how to measure and improve the spatial resolution in TERS imaging, (c) how to apply the technique to understand the structure-property relationship of nanoscale structures and chemical characterisation of organic and biosurfaces at the nanoscale. We are currently collaborating with Prof Mark Welland (Nanoscience Centre, University of Cambridge) and Dr Ji-Seon Kim (Imperial College, London) to develop this technique and its applications.

Selected Publications

[1] Fabrication of gold tips suitable for Tip-Enhanced Raman Spectroscopy, C Williams and D Roy, J. Vac. Sci. Tech. B 26(5): 1761 2008

[2] Nanoscale imaging of carbon nanotubes using Tip Enhanced Raman Spectroscopy in reflection mode. D Roy, J Wang and M Welland, Faraday Discuss. 132: 215-225. (2006)

[3] High resolution Raman imaging of single wall carbon nanotubes using electrochemically etched gold tips and a radially polarized annular beam, D Roy and C Williams, J. Vac. Sci. Technol. A 28: 472. (2010)