Combined surface- and tip-enhanced Raman spectroscopy (SERS and TERS, respectively) experiments for CN- adsorbed at Au-surfaces are presented. STM tip-induced frequency shifts for the CN-stretch vibration are observed. This effect is attributed to a distinct weighting of the individual contributions to TERS, depending on the particular field distribution, which peaks underneath the tip apex and drops quickly beyond this region. (C) 2003 Elsevier B.V. All rights reserved.