In situ FTIR study of 2-chloropyridine adsorbed on Au(111) and Au(110) electrodes

2-chloropyridine (2Clpy) adsorbed on Au(111) and Au(110) electrodes in 0.1 M KClO4 containing 2 mM 2Clpy has been investigated using in-situ infrared spectroscopy and differential capacity measurements. For both the electrodes, an in-plane ring vibration due to N-bonded 2Clpy was observed, which was accompanied by a loss in the in-plane ring vibrations due to dissolved 2Clpy. However, the integrated band intensity ratios between the adsorbed 2Clpy and the loss of dissolved 2Clpy for both electrodes are quite different in all potentials measured. The relative band intensity of the N-bonded 2Clpy for Au(110) is much stronger than that for the Au(111). This indicates that for the Au(111) the adsorbed 2Clpy is mainly flat type or the tilt angle of the N-bonded 2Clpy is large. It can be explained by the configuration of adsorbed 2Clpy on the electrode surface. For Au(111) terrace, N-bonded configuration is obstructed by the presence of Cl atom. There is no obstruction for the Au(110) step if the N-bonded 2Clpy is adsorbed on the overtop layer. (C) 2002 Elsevier Science Ltd. All rights reserved.