In situ scanning tunneling microscopy in electrolyte solutions

• Published in: Progress in surface science 1998-07, Vol.58 (3), p.121-247
• Main Author: Itaya, Kingo
• Format: Article
• Language: English
• Subjects: Chemistry; Condensed matter: structure, mechanical and thermal properties; Electrochemistry; Exact sciences and technology; General and physical chemistry; Physics; Solid surfaces and solid-solid interfaces; Study of interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0079-6816; 1878-4240
• DOI: 10.1016/S0079-6816(98)00022-7

Until recently, there had been only few in situ methods available for the structural determination of an electrode surface in solution at the atomic level. Now, several recent investigations have demonstrated scanning tunneling microscopy (STM) to be a powerful new technique for in situ characterization, with atomic resolution, of surfaces under potentiostatic control. The object of this review is to highlight some of the recent progress made, mainly, but not exclusively, in the author's laboratory, on in situ STM with atomic resolution. The review is focused on several selected topics, including structures of specifically adsorbed anions, underpotential deposition, adsorption of organic molecules, and electrochemical dissolution of metals and semiconductors. A combination of in situ STM and ex situ ultrahigh vacuum techniques has revealed detailed atomic structures of various adlayers, particularly iodine adlayers on Au, Ag, and Pt electrodes. It was recently demonstrated that aromatic molecules such as benzene adsorbed on Rh, Pt, and Cu can be clearly “seen” while the electrode is immersed in electrolytic solution. The atomic structures of semiconductor surfaces of Si, GaAs, and InP were successfully imaged in solution. Furthermore, it has been established that dynamic processes of electrochemical etching of metals and semiconductors can be followed by in situ STM. The work on semiconductors may well form the basis of development of a technology for preparing atomically flat substrate surfaces, which are expected to be required by the semiconductor industry of the next generation.