Cathodoluminescence investigation of gold prisms in the STEM: (a) and (b) are bright field TEM images and (c) and (d) are the cathodoluminescence intensity maps recorded in STEM mode from particles (a) and (b) respectively. The change in size of the prism leads to a change in the local surface plasmon resonance modes causing a change to the spatial and spectral (not shown here) distribution of luminescence.