We present a low-temperature scanning tunneling spectroscopy study of the $\text{Au}\left(111\right)$ and of the $\text{Cu}\left(111\right)$ surface states showing that their binding energy increases when the tip approaches towards the surface. This result, supported by a one-dimensional model calculation and by a comparison to existing photoemission spectroscopy measurements, confirms the existence of a tip-induced Stark effect as previously reported for $\text{Ag}\left(111\right)$ [L. Limot et al., Phys. Rev. Lett. 91, 196801 (2003)], and suggests that this effect is a general feature of scanning tunneling spectroscopy.

• Received 3 February 2004

DOI:https://doi.org/10.1103/PhysRevB.70.033401