Finite element simulations of tip-enhanced Raman and fluorescence spectroscopy.
Finite element electromagnetic simulations of scanning probe microscopy tips and substrates are presented. The enhancement of the scattered light intensity is found to be as high as 10(12) for a 20 nm radius gold tip, and tip-substrate separation of 1 nm. Molecular resolution imaging (< 1 nm) is achievable, even with a relatively large radius tip (20 nm). We also make predictions for imaging in aqueous environments, noting a sizable red shift of the spectral peaks. Finally, we discuss signal levels, and predict that high-speed Raman mapping should be possible with gold substrates and a small tip-substrate separation (< 4 nm).
Institute of Materials and Processes, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JL, United Kingdom. andy.downes@ed.ac.uk
Andrew
A
Downes
Donald
D
Salter
Alistair
A
Elfick
D000388:Air; D003198:Computer Simulation; D020342:Finite Element Analysis; D013050:Spectrometry, Fluorescence; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry
D014867:Water