In situ synchrotron far infrared micro-spectroelectrochemistry with a grazing angle objective

We demonstrate the use of a grazing angle objective attachment to carry out in situ far infrared micro-spectroelectrochemistry at a copper electrode on a nano-scale. A thin-layer spectrochemical cell made out of Teflon was used, fitted with a 20-μm thick Mylar window; the working electrode was 500 μm in diameter. Measurements were carried out in 0.1 M NaOH solution as a function of applied potential between -1.4 and 0 V vs a Hg/Hg2SO4 reference electrode. Spectra were obtained with excellent signal to noise ratio for the surface oxide film, formed on copper electrochemically with less than 1 nL of active solution volume. The surface film at 0 V was about 130 nm thick and consisted mainly of CuO, with possibly some Cu(OH)2 also present. This interpretation is consistent with previous works and thermodynamic calculations. The technique should be useful in other investigations and the further development of electrochemical surface science.