Scanning tunneling microscope (STM) induced light emission from nano structures comprising silicon dangling bonds on deuterium terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel mechanism involving optical transitions between a tip state and localized states on the sample surface. The wavelength of the photons can be varied by the bias voltage of the STM. The spatial resolution of the photon maps is as accurate as that of STM topographic images and the photons are emitted from a quasi-point source with a spatial extension similar to the size of a dangling bond.