OPTICAL-RESPONSE OF THIN PLASMA-POLYMER FILMS WITH NONSPHERICAL SILVER NANOPARTICLES

The size and shape of silver nanoparticles which are embedded in a pla sma-polymer matrix were obtained by transmission electron microscopy a nd analyzed with optical image processing. We used a sample in which s ilver particles were present before and after reshaping caused by ther mal annealing in adjacent regions. As most of the particles appeared a s elongated rotational ellipsoids, the major and minor half axis were determined for each particle. We adopted the model of Gans in the Rayl eigh approximation to calculate for each investigated particle the ext inction spectra from 4000 cm(-1) to 35 000 cm(-1) using the data from the image processing. The various spectra for 368 silver particles wer e added to get total extinction spectra for the sample as deposited an d after reshaping, respectively. We found good agreement with the expe rimental spectra. The blue shift of the plasma-resonance absorption, w hich occurs due to the reshaping of the silver particles during therma l annealing, was also confirmed by using only changes in the particle sizes and shapes.