Sum frequency generation spectroscopy and double-layer capacitance studies of the 1-butyl-3-methylimidazolium dicyanamide-platinum interface

The orientation of the cation and the anion of 1-butyl-3-methylimidazolium dicyanamide at the platinum-liquid interface are reported, using sum frequency generation (SFG) spectroscopy. Results suggest that the imidazolium ring in the cation tends to lie flat at the surface of the electrode at negative potentials but is repelled at positive ones, while the anion is strongly adsorbed at the surface of the platinum at more positive potentials with its [C.sub.2] axis aligned with the surface normal.