EMISSION FREQUENCY OF SINGLE MOLECULES AT A METALLIC APERTURE - THE APPLICABILITY OF THE IMAGE THEORY

The simple classical image theory is applied to describe the shift in emission frequencies for single molecules at a metallic aperture. The validity of this approach is further clarified using well known result s for the case of molecules at flat surfaces, For molecules oriented p arallel to the plane of the aperture, a numerical example shows that a side from the general small red shift, the two orthogonal ''in-plane'' directions behave quite differently in their emission frequencies as they are scanned from the center to the edge of the tip, suggesting a possible way of distinguishing the two orientations through observatio n of their emission frequencies.