DETERMINATION OF THE THICKNESS OF PLASMON CARRIER LAYERS BY THE PHOTOMETRIC METHOD

Abstract

The influence of design and technological factors, in particular, the deviation of the thickness of the plasma-carrying layer from the nominal value, introduces uncertainty into the measurement by the method of surface plasmon resonance. The effect of the thickness of nanoscale films of surface plasmon resonance sensors on the characteristics of these sensors is shown in the work using the method of numerical modeling. An experimental study of the transmission spectra and reflection characteristics of gold films of different thicknesses was conducted and consistency with theoretical calculations was established. Transmittance coefficients were used as an informative parameter for estimating the thickness of nanosized gold films of surface plasmon resonance sensors. Not only the difference in the angular positions of the resonance and the intensity of the reflected light in it, but also the different width of the resonance characteristics in the region of the minimum and the shape of the intensity graph at angles smaller than the critical one are characteristic for samples with different thicknesses. The correlation coefficient between the thickness of the studied samples and the corresponding transmission coefficients at a wavelength of 532 nm is r = - 0.943. This means that there is a correlation between the parameters, there is a linear functional dependence between them. An empirical dependence of d=1100.7712·T-0.3328 with a high degree of correlation (r = - 0.943) was established between the thickness and the corresponding transmittance coefficients of gold films for λ=532 nm. With this relative empirical error of thickness determination does not exceed 3%. The dependence of the maximum transmission spectrum Tλmax of nanosized gold films on the thickness of these films was experimentally established. At this step, the thickness determination did not exceed 1 Ǻ. The research data show the prospects of using the monochromatic photometric method to determine the thickness of plasma-carrying nanoscale layers.