Cathodoluminescence, i.e., light emission upon electron irradiation in a scanning electron microscope was used to investigate the local excitation of surface plasmons in free standing tips and electrochemically deposited nanoparticles. Additional cathodoluminescence measurements on tip-surface-systems were done to locally excite plasmons in the gap. A scanning tunneling microscope mounted inside the vacuum chamber of the SEM was used for controlling the distance between tip and surface
