Ellipsometry Study of the Adsorption of Molecules at Electrolyte Interfaces with Gold and Stainless Steel

✍ Scribed by D. Beaglehole; B. Webster; S. Werner

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 172 KB
• Volume: 202
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5475

✦ Synopsis

ties-we were particularly interested in whether the ad-We describe an ellipticity study of the adsorption onto gold and sorbed layers could be desorbed with changing potentials. Type 304 stainless steel of the molecules bovine serum albumin The adsorbed quantities were determined using a quickly (BSA), sodium dodecyl sulfate (SDS), and polyethylenimine responding ellipsometer. (PEI) in sodium perchlorate electrolyte solutions. The ellipsome-Gold is inert over a range of electrode potentials. In pure tric response is made of two effects, one due to surface-charging electrolytes a change in the reflectance as the potential is of the metal electrodes, and the other due to adsorption. The varied was first observed by Feinlieb (1). Prostak and Hansurface-charging effect is much larger for gold than for stainless sen (2) showed that these were caused by changes in the steel. Misleading estimates for the adsorption are obtained if this

dielectric constant of a thin outer layer of the metal and not charging response is not taken into account. We find that for the most part the adsorbed layers are not sensitive to the applied by changes in the electrolyte. The ellipticity is also affected potential, and only on one occasion did we observe reversible deby changes in the bias potential. The spectral variation of sorption with varying potential. The surface-charging effect is not the ellipticity change is different from that of the reflectivity, altered by BSA (the largest molecule), but SDS and PEI show but in another paper (3) we show that it is also determined evidence for changes in the surface-charging effect (and thus in by the outer layer of the gold electrode. We show there the Stern layer) and changes in conformation. ᭧ 1998 Academic Press that a simple ''surface-charging'' model using data from