STM induced photon emission at the liquid-solid interface

We have observed STM-induced photon emission at the liquid-solid interface. The luminescence spectra as well as the photon intensity are recorded simu ltaneously with the measurement of the scanning tunneling microscopy (STM) topography image using an intensified charge coupled device detector and a spectrograph for the spectrum measurements, and a photomultiplier for the p hoton intensity measurements. The measurements of STM induced luminescence are made in non-aqueous liquid which has a wide potential window. The lumin escence could only be recorded for 1,4-dioxane at the STM bias voltage at 5 V, but other liquids were also tried. The reason behind this result is dis cussed in relation to the dielectric constant of the liquid. (C) 1999 Elsev ier Science B.V. All rights reserved.