Design and performance of a new infrared reflection accessory for spectroelectrochemical studies

A novel spectroelectrochemical cell based on a hemispherical window which fits in the sample compartment of a center-focus FT-IR spectrometer is described. The ZnSe hemisphere serves to collimate the beam, provide near-critical angle reflection, lower first-surface reflection losses, and reestablish the instrument focal point. The optics of the spectroelectrochemical accessory include only two folding mirrors, the IR polarizer, the ZnSe window, and the electrode. The optimum angle of incidence for the reflection experiment is determined from calculated mean-squared electric field strengths. Typical potential difference spectra are presented for varying degrees of signal optimization, and the gains in signal-to-noise ratios are reported.