INVESTIGADORES
VELEZ Patricio
artículos
Título:
Experimental and theoretical studies of l-cysteine adsorbed at Ag(1 1 1) electrodes
Autor/es:
E. SANTOS; L. AVALLE; K. POTTING; P. VÉLEZ; H. JONES
Revista:
ELECTROCHIMICA ACTA
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Año: 2007 vol. 53 p. 6807 - 6817
ISSN:
0013-4686
Resumen:
We have investigated l-cysteine adsorbed on Ag(1 1 1) electrodes under different conditions. We have employed experimental and theoretical approaches to obtain a better understanding of the adsorbed layer. An estimation of the coverage from charge measurements and the second harmonic response shows C3v symmetry for the interface indicating a (√3×√3)R◦30 overlayer. The theoretical calculations show a variety of different structures with local adsorption energy minima. Particularly, under special initial conditions, zwitterionic structures adsorbed at different sites have been found. This can account for the multiplicity of redox processes observed experimentally below the potential of zero charge. The presence of an external field produces the stabilization of the zwitterion by interaction of the amino/carboxylic groups with the substrate.