ON THE DIFFERENCE BETWEEN LIGHT-EMISSION VERSUS VOLTAGE CHARACTERISTICS IN AIR AND IN ULTRAHIGH-VACUUM

The difference between the STM light emission versus voltage character istics L ( V) for the tunneling pp between two metals obtained in air and in ultrahigh vacuum (UHV) is explained. It arises because the dist ance between the tip and the sample in air has a stronger dependence o n the voltage applied than in UHV. In air the different tip-induced pl asmon modes can be observed not only in the spectrum of the emitted li ght as is the case in UHV, but in the L ( V) characteristics as well.