OBSERVATION OF PLASMON-ENHANCED OPTICAL EXTINCTION IN SILVER-COATED SILVER BROMIDE NANOPARTICLES

Silver bromide nanoparticles exposed briefly to intense UV light in the presence of ethylenediaminetetraacetic acid (EDTA) have optical extinction spectra similar to those computed for distributions of silver-coated silver bromide nanoparticles. With longer exposure times the plasmon resonance maximum is shifted to shorter wavelengths, a result consistent with theory so long as the coat thickness increases with exposure to light. The resonance maximum of the distribution of coated particles can be controllably shifted from 400 up to 700 nm.