[6a-A414-1~10] 3.8 Optical measurement, instrumentation, and sensor

[6a-A414-10] Microscopic absorption measurement of adsorbed molecules by using focused surface plasmons

〇Hiroki Sato¹, Hiroshi Kano¹ (1.Muroran Institute of Technology)

Keywords:Surface plasmon, Microscopic absorption measurement, Molecular adsorption

In the measurement of light absorption due to adsorption of absorptive molecules, surface plasmons are able to enhance absorbance from the one obtained by the attenuated total reflection (ATR) method. In this presentation, we propose a method in which focused surface plasmons are employed to measure local absorption. A theoretical calculation of the reflectance as a function of spatial frequency by assuming an absorptive ultra-thin layer on a gold surface shows a deeper and wider dip compared to a bare surface. Qualitative properties found in the measured plots of reflected light intensity as a function of spatial frequency coincides with the theoretical calculations.