SERS spectra of Au/Au core/satellite particles were recorded using a confocal Raman microscope (WITec, model alpha300 R) with a grating monochromator (30 cm focal length) and an EM-CCD. A 40x air objective with a NA of 0.6 was used. Raman scattering was excited by a He-Ne laser (632.8 nm line) with a laser power of 5 mW at the sample.