CHERENKOV EFFECT IN THE CONTEXT OF SCANNING-TUNNELING-MICROSCOPY

The intensity of the light emission from the STM tunneling junction between two metals is shown to depend exponentially on the tunneling distance. Assuming the exponential decay constant to be equal to the mean wave vector of the surface plasmons excited by the tunneling electrons, the plasmon phase velocity is estimated to be two times smaller than the Fermi velocity of the electrons. A new theoretical description of the light emission phenomenon based on a Cherenkov-like resonant interaction between the tunneling electrons and the surface plasmons is developed.