Refined interpretation of optical extinction spectra of nanoparticles in plasma polymer films

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to 50000 cm^-1, exhibiting an extinction maximum that could be assigned to the corresponding long-axis surface plasmon excitation in the spheroidal noble metal particles. For simulation of the measured spectra, the model of Gans [Ann. Phys. 37, 881 (1912)] was used to calculate the optical extinction spectrum for each analyzed particle in a sample. The various spectra of more than 500 particles were added up to get the total extinction spectrum of the sample, yielding very good agreement with the measured spectra. A remaining blueshift of the computed spectra compared to the measured spectra could be explained by considering electromagnetic interaction among the particles.