Narrowband luminescence of copper in the presence of gold nanoparticles

Narrow bands were experimentally revealed in the spectrum of copper under a layer of gold nanoparticles. Luminescence was excited with a He–Ne laser (6328 $\mathring{\mathrm{A}}$). The spectra of films of individual metals contained no similar bands. Experimental conditions and recorded spectra were presented, and some possible explanations of the observed effect were discussed.