SENSITIVITY AND REPRODUCIBILITY IN INFRARED SPECTROSCOPIC MEASUREMENTS AT SINGLE-CRYSTAL ELECTRODE SURFACES

The benefits of optimized in situ infrared measurements performed on single-crystal platinum electrodes are described in this paper. By using a hemispherical window both as a lens and as the IR-transparent wall of the thin-layer electrochemical cell, several signal-enhancing effects are achieved: low first-surface reflection losses, near-critical angle reflection, and beam collimation. In addition, the physical optics of this novel sampling attachment provide interactive tools for positioning the electrode in the cell via the evolving interferogram. Thus, both sensitivity and reproducibility are improved. The effects of poor optical throughput are demonstrated, and a measure of the expected merit for in situ reflection/absorption spectroscopy is presented. Examples are given of adsorption processes from sulfuric acid solutions and for the oxidation of glucose on both Pt(111) and Pt(100) electrode surfaces.