text: The experimental set-up used to carry out UV-Vis absorption SEC measurements depends on the chosen configuration and the characteristics of the analyte. The experimental set-up is composed of a light source, a spectrometer, a potentiostat/galvanostat, a SEC cell, a three-electrode system, optical elements to conduct the light beam, and a computer for data collection and analysis. Currently, there are commercial devices that integrate all these elements in a single instrument, simplifying significantly the SEC experiments.
  * Light source: provides the electromagnetic radiation that interacts with the sample while the electrochemical process is taking place. A specific source is required for the UV-Vis spectral region, being the most common the deuterium/halogen lamp.
  * Spectrometer: instrument that allows measuring the properties of the light in a certain region of the electromagnetic spectrum. It uses a monochromator to separate the different spectral wavelengths of interest emitted by the light source. A diode-array detector can be used to obtain time-resolved spectra. For UV-Vis spectroelectrochemistry, spectrometer must be specific for UV-Vis spectral region.
  * Potentiostat/Galvanostat: electronic device that allows controlling the working electrode potential regarding to the reference electrode or controlling the current that passes respect to the auxiliary electrode.
  * Three electrode system: consists of a working electrode, a reference electrode and an auxiliary electrode. This system can be simplified by using screen-printed electrodes that include the three electrodes on a single holder.
  * Spectroelectrochemical cell: device in which the solution and the system of three electrodes is located, avoiding possible interference in the optical path. It is the link between the electrochemistry and the UV-Vis absorption spectroscopy.
  * Devices to conduct the radiation beam: lenses, mirrors and/or optical fibers. The last ones conduct electromagnetic radiation over great distances with hardly any losses. In addition, they simplify the optical configurations because they allow working with a small amount of solution. Optical fibers make easier to conduct and collect light near the electrode.
  * Analysis and data collection devices: a computer collects the signals provided by the spectrometer and potentiostat that, using a suitable software, treats, analyzes and interprets the signals.