The light emission spectra of individual Au nanoparticles induced by a scanning tunnelling microscope (STM) have been investigated. At the same time the nanoparticles were characterized by STM measurements. Two-dimensional ensembles of tunnel-coupled Au nanoparticles were prepared by thermal evaporation onto a native oxide silicon wafer in ultrahigh vacuum (10-10 mbar). We present the experimental evidence of photon emission from Au nanoparticles excited with W tip in the tunnel (tip voltage lower than 5 V) and field emission modes (tip voltage higher than 5 V). In the first case the tunnel current has inelastic component that is used for the tip-induced plasmon excitation. The photon emission that corresponds to them is characterized by a maximum at 1.62 eV. In the second case the photon emission spectrum is more complicated. The photon emission spectrum for Au nanoparticle obtained after subtraction of photon emission from the substrate (the native oxide silicon wafer) is characterized by peaks at 2.22 and 1.45 eV connected with the Mie plasmon and the density of unoccupied states above the Fermi level, relatively. The low-energy peak at 1.45 eV has not been discussed in literature. It was more pronounced then in other publications most likely due to more blunt W tip in our experiment and consequently larger applied voltage (the Au nanoparticle size was a few nanometers in all cases). The use of an STM in the field emission mode with the light signal detection allows implementing of low-energy electron-photon spectroscopy (inverse photoemission spectroscopy).