I-V characteristics of isolated porphyrin molecules display a minimum in I/V2 at a characteristic "transition voltage" V m. Fluctuations at the molecular contact effect changes in V m and from repeated measurements both its time development and statistical behavior is determined. This contrasts with the more stable contact over a self-assembled monolayer with parallel conduction through many molecules.
- contact asymmetry
- scanning tunneling microscopytransition voltage spectroscopy
- single molecules