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Zusammenfassung:
This chapter focuses on scanning tunneling microscopy (STM) studies of tautomerization within a single molecule adsorbed on a surface. First, the operation principle and theory of STM is briefly described and then several examples from recent studies are discussed. STM can be used to manipulate single atoms and molecules, thereby enabling to build artificial structures on surfaces. The trans-trans tautomerization of a single naphthalocyanine molecule, that is, the transfer of both H atoms in the cavity among the pyrrole rings can be induced if a voltage pulse larger than 1.4V is applied to the molecule. Tautomerization within porphyrin and phthalocyanine derivatives has been studied at cryogenic temperatures and induced by a voltage pulse of the STM. The tautomerization mechanism has been attributed to inelastic electron tunneling. Time-resolved STM methods with the order of nanoseconds or picoseconds can be achieved by combining a short electric or optical pulse.
