Near-field spectroscopy of surface excitations

Summary form only given. We provide a powerful tool to describe near-field spectroscopic effects in thermal emission of light. Due to the possibility of measuring near-field spectra by using near-field optics techniques, the work could find applications in solid-state spectroscopy. It should also be helpful in modeling nanoscale radiative transfer of energy, where transfer through non-radiating modes is of fundamental importance. We show that near-field excitations dramatically influence the spectrum of the emitted radiation. For example, we study a SiC surface in the infrared part of the spectrum. The energy density has a spectrum which changes strongly during the transition from the near field to the far field. The near-field spectrum is a signature of the excitation of surface-phonon polaritons at wavelengths around /spl lambda/=11.3 /spl mu/m. We show that the features of this spectrum can be interpreted using the density of states of the surface modes.