We present herein silver nanoparticles about 4 nm in diameter coated with a binary mixture of 1-octanethiol and 2-(2-{2-[(6-mercaptohexyl)oxy]ethoxy}ethoxy)ethanol. These particles show an affinity towards optically active Eu3+ ions. The effect of the nanoparticle on the characteristic emission peaks of Eu3+ is investigated. We use the variation in emission spectra of the ion to establish its binding to the nanoparticles.