Galvanostatic etching

The Si wafers ((111) p-type with 2-11 icm) were galvanostatically etched in 1 1 2 HF (40 %)/H20/Et0H (98 %) at 30 mA/cm for 10 min. After etching the PSLs were washed with deionized water, dried under vacuum and characterized by vibrational spectroscopy (transmission FTIR). 

Desorption/ionization on silicon. Another matrix-free approach for the analysis of small molecules is to use modified porous silicon surfaces [61]. A separate name, desorption/ionization on silicon (DIOS), has been coined for this technique [62]. In this approach, the sample is dispensed directly onto a modified porous silicon surface (e.g., silylated porous silicon) and laser-desorbed from the surface. The silicon surface is prepared from flat crystalline silicon by galvanostatic etching. 

They used the same approach for the quantitative study of acid-induced dissolution of enamel. A UME was used to generate a flux of protons galvanostatically just above a sample surface. This produced etch features in the sample, which were characterized by white light interferometry. The technique has been applied to bovine enamel where understanding the kinetics of dissolution is important in the context of acid erosion. Dissolution has been observed as a fast process, but the high rates of mass transport in SECM allowed the surface kinetics of dissolution to be evaluated. 

The control apparatus would typically consist of a potentiostat with a sufficiently large current output to support the total photoelectrochemicai process. Most examples of photoelectrochemicai processing are carried out at constant potential, but some examples exist of galvanostatic control. The course of the photoelectrochemicai process is monitored as the Integrated current, which may be related directly to the amount of etched or deposited material. A coulometer or integrating computer may be used for this purpose. 

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