A new method to perform scanning electrochemical microscopy (SECM) and topography simultaneously is described here. The new method uses a conventional scanning microelectrode to sense species released by local electrochemical reactions on the surface of a sample, combined with shear-force feedback to maintain the probe at a constant distance from the surface of the material. By using shearforce feedback, larger electrochemical currents can be detected at the microelectrode because the probe is scanned at a closer distance from the surface of the sample. The new method has yielded high lateral resolution topography and SECM images are reported here.

A new instrumental technique that combines scanning electrochemical microscopy and scanning photoelectrochemical microscopy is described. This technique is capable of monitoring electroassisted and/or photoassisted reactions on semiconductor surfaces either concurrently or sequentially. The instrument uses a probe which consists of an optical fiber coated with gold and isolated from its surrounding environment with a polymer film. Measurements of the electroreduction of Br2 at the gold ring which had been generated by photo-oxidation of Br on a 50 ,&, thick TiO2 film on Ti are discussed. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-17 to IP

Scanning electrochemical microscopy (SECM) in ferrocyanide and bromide solutions was used to locate active sites (pitting precursors) on polycrystalline Ti where oxidation of Br and Fe(CN) was possible. Analysis of the electroctrochemically active sites was done by using electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM), and in situ confocal laser scanning microscopy (CLSM). Inmost cases, the active sites were found to be associated with particles (inclusions) which contained mainly Al and Si; however some other areas not associated with particles were also found to be active. Although the size of the inclusions was normally smaller than 10 p.m, as revealed by SEM and AFM imaging, in some cases larger particles were also found. Pitting corrosion tests in bromide solution at potentials above 1.5 V5 followed by EDX analysis inside the pits and in situ CLSM observation, confirmed that most of the localized attack started in the areas where particles had been located.

A technique for combining scanning electrochemical microscopy (SECM) and scanning photoelectrochemical microscopy (PEM) is described. The experimental setup is described and the several modes of operation are discussed. The electrochemical characteristics of the probe, collection efficiency, current efficiency, and the coupling efficiency for the two techniques, are examined in several model systems. SPECM was used to identify pitting precursor (PPS) sites on a titanium sample with a 50 A oxide layer in an acidic KBr solution. It was found that the PPS site could be imaged photoelectrochemically and that the photocurrent is reduced at the PPS.

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