Localized interaction of single porphyrin molecules with oxygen vacancies on TiO2(110).

Alterations in the electronic structure of adsorbed zinc(II) etioporphyrin I (ZnEtio) through interaction with bridging oxygen vacancies on TiO(2)(110) are studied by scanning tunneling microscopy and spectroscopy at cryogenic temperatures under ultrahigh vacuum (UHV) conditions. Upon lateral manipulation of ZnEtio molecules above surface oxygen vacancies, the highest occupied molecular orbital shifts away from the Fermi level. The magnitude of the shift rapidly decreases with increasing distance of the molecule from the vacancy, indicating a highly localized interaction.