Simulation for Local Detection of Surface Plasmon Resonance Combined with STM

Abstract

We have made a SPR(Surface Plasmon Resonance) spectrometer combined with STM(Scanning Tunneling Microscope) to detect the nanoscale signal. The nanoscale signal from SPR measurements should be detected by approaching STM to the surface of the sample film using the effect of the near field due to the presence of STM tip, on the SPR angle, reflectivity and polarization change. To confirm the possibility of SPR in nanoscale, we have carried out the simulation for the detection of local SPR reflectivity for inhomogeneous sample on a nanometer scale. The layer model for STM tip has been employed to the measuring object in layers including prism, sample and air. On the basis of the present simulation, STM Tip effect on SPR reflectivity is less than ～0.7% of incident light intensity(beam size of 50μm) for the sample with homogeneity variation of 10-50%. We have discussed that the nanoscale measurements of SPR combined with STM can be detected by using small size of laser beam less than 50μm and the STM tip positioning in the range from 1nm through 500nm.