Adsorption of Cysteamine at Copper Electrodes as Studied by Surface‐Enhanced Raman Spectroscopy

Abstract

The adsorption of cysteamine on a roughened polycrystalline copper electrode in acidic solution has been studied, in‐situ, using surface‐enhanced Raman spectroscopy (SERS). It was shown that gauche/trans rotational isomerization of the adsorbate depends on the solution concentration of cysteamine. Coadsorption of oxyanions (ClO4 − and SO4 2 −) with cysteamine has been detected spectroscopically. At relatively high cysteamine concentrations (10− 4 M) the physisorption of oxyanions was evidenced by a minor shift (within 5 cm− 1) in the totally symmetric vibrational frequency, as compared with the solution species, and narrow bandwidth (16 cm− 1). In contrast, the large downward frequency shift of coadsorbed SO4 2 − ions (12 cm− 1) and substantial broadening of the band (bandwidth, 29 cm− 1) indicated chemisorption of the sulfate anions on the copper electrode at low cysteamine concentrations (10− 7 M).