FIELD ENHANCEMENT OF OPTICAL RADIATION IN THE NEARFIELD OF SCANNING PROBE MICROSCOPE TIPS

A brief outline of the methods and approaches in the theory for field enhancement of laser radiation in the nearfield of a scanning probe mi croscope tips is given. The simple analytical ''small spheroid model'' (mainly used in Surface Enhanced Raman Spectroscopy) as well as a mor e realistic numerical model based on the boundary element method are u sed for field enhancement calculations on the tip apex. The small sphe roid model gives a rough estimation from below for tips with spheroid geometry, whereas the numerical model can take into account arbitrary tip geometry and include the effect of substrate surface. Tremendous f ield concentration with nanometer localization for certain tip and sub strate materials is used for applications in surface nano modification with laser radiation. Experimental data supporting the surface modifi cation due to the enhanced field mechanism are presented.