Nonlinear Spectro-Electrochemical Flow Cell
The Nonlinear Spectro-EFC is a multifunctional spectral cell developed for nonlinear laser spectroscopy combined with electrochemical methods. However, its double cone geometry and selection of window materials make it uniquely suitable for a broad range of spectral and diffraction techniques to obtain in situ chemical information about thin films and adsorbed species during electrochemical reactions.
The cell is built from three main elements: the sample mount with tantalum, dry electrical contact to the working electrode surface, the chamber in which the electrolyte inlet and outlet together with a reference and counter electrodes are mounted in either a two-or three-electrode configuration and the lid in which the window is mounted. In the chamber, the oval platinum wire counter electrode assures uniform distribution of the field lines along the path to the working electrode, while the 6 mm diameter port can be fitted with a standard reference electrode, a plug, or a supplementary sensor/probe.
The cell is configured to have a pathlength of 2.25 mm through the electrolyte to ensure free diffusion of ions and counter ions. The front working distance is equal to the electrolyte pathlength plus the window thickness, typically 1 mm but dependent on the material, generally 3.25 mm. The rear working distance is dependent on the thickness of the working electrode support and the applied electrochemically active layer.
In a typical configuration, the window material is selected to be transparent to the spectral region of interest and the sample is a thin film of electrochemically active material deposited on a rigid or flexible substrate which can be transparent or opaque depending on the experimental requirements. The cell has a 21 mm clear aperture, and both the sample holder and lid have conical profiles and allow a Θ of up to 60° off normal for the incident, transmitted, reflected, and scattered/diffracted light. This geometry facilitates the use of large-diameter objective lenses, or other optics, to be used for a range of measurement modes from the simple transmission to diffuse reflectance to specular reflectance and grazing angle methods. Further, through appropriate window and working electrode substrate selection, in situ measurements using the spectral regions from FTIR to x-rays are possible, thus opening the door for nonlinear methods such as sum frequency generation (SFG), second harmonic generation (SHG), pump probe spectroscopy, SAXS and WAXS in transmission and grazing angle modes, grazing angle FTIR of films on IR transparent substrates, as well as various microscopy and imaging methods.
The Nonlinear Spectro-EFC cell elements are constructed from materials that are inert to the sample environment (PEEK, Fluorocarbons), and either aqueous (FKM) or organic solvent (FFKM) compatible O-Rings can be installed to meet electrolyte requirements. The construction is gas-tight and gas purging of the electrolyte via an external reservoir can be used when the removal and exclusion of contaminants such as oxygen or the introduction of a gas phase reagent is required.
This cell was developed for thin film and film/electrolyte interface analysis by a variety of methods including but not limited to nonlinear laser (NLS) spectroscopy methods. It can also see application in in situ x-ray applications including scattering and/or absorption methods, as well combined set-ups at synchrotron facilities. Further, it can be used as a (micro) Raman cell or with a number of advanced microscopy methods, as well as conventional spectroscopy instruments.
Maximum Θ angle value: 60°
Nominal exposure area: 3.5 cm2 (21 mm dia.)
Electrolyte volume: 7 mL
Optical path (including window): 3.25 mm
Electrode plug diameter: 6 mm
1 x chamber
1 x Ag/AgCl or Ag/Ag+ 30 mm reference electrode
1 x Metal wire auxiliary electrode – ST 0.6/220 mm, platinum
1 x sapphire window (other materials available on request)
1 x lid
1 x WE tantalum contact
1 x sample mount
1 x plug