Molecular electronic transitions observed by inelastic tunneling spectroscopy

Abstract

The method of inelastic tunneling spectroscopy has been extended to the observation of electronic transitions of organic molecules. The aim of this work was to study the selection rules and to analyze the shape and strength of the observed transitions. We find that both singlet-singlet and singlet-triplet transitions can be observed with roughly the same intensity, but the peaks are found to be rather wide. The first point is explained by the interaction mechanism between the tunneling electrons and the molecules, the second by the interactions of the molecules with their environment.