Prismatic windows

Figure 2.46 Schematic diagram showing the angle of incidence at the electrode for (a) an angle of incidence of 65° at a plate window (W), and (b) the incoming ray incident normal to the face of a prismatic window (P), having a bevel of 65 , assuming RM Vn)( = 1.33, Venl = 0, nwind(> = 1.4, kwiBdow = 0, ni([ = 1, and k, = 0. TL = thin electrolyte layer, E = electrode,...

FTIR experiments were carried out with a Bruker Vector 22 spectrometer equipped with a MCT detector. The electrochemical IR cell, fitted with a 60° CaF2 prismatic window, was provided with an inlet and an outlet for the solutions to allow the electrolyte exchange under potential control. For each spectmm, 128 interpherograms were collected at a resolution of 8 cm-1. Parallel (p) and perpendicular (s) polarized IR light were obtained from a BaF2-supported A1 grid polarizer. The spectra were represented as a ratio, R/R0, where R and Ra are the reflectances corresponding to the sample and reference spectra, respectively. 

Fig. 39. Angle of incidence of IR light on reflective electrode (Q,) (a) for various angles of incidence on a plate window and (b) for various angles of the faces of a prismatic window at normal incidence.

The equations for a system consisting of metallic surface/thin-film elec-trolyte/prismatic window were developed by Seki et al. [29]. Briefly, the equations are... 

The experimental setup for in situ infrared for electrochemical studies requires the construction of an electrochemical cell equipped with a window transparent to the infrared radiation and stable in aqueous electrolytes as used for the electrochemical studies. The window can be either flat or prismatic and is usually placed at the bottom of the cell. The prismatic window allows a more favorable angle of incidence. 

An important detail is the difference between the reflectivity using a flat window or a prismatic window for the in situ spectra. Simulating a change in absorbance in the thin-fllm layer, that is, a change in the solution composition, data of reflectivity are shown in Fig. 11 (a, b)... 

There is a maximum for 70° of incidence angle between 40° and 90° and there is a angle at the window. When a prismatic pronounced maximum around 70°. window is used, the radiation reflectivity The consequence of this behavior is that is strongly dependent on the incidence when a prismatic window is used, the... 

Fig.n Si mulated change in reflectivity for the system (a) flat window/electrolyte/metal for a change in the absorption in the electrolyte layer (note the interference fringes caused by the internal reflections) and (b) prismatic window/electrolyte/metal. The parameters used in the simulation are n- =1.0 (air) n2 =. 4 (Cap2 window) /13 = 1.32 + i0.015 (electrolyte) and n4 = 10.9 + 15.6 (Pt). Electrolyte film thickness 2.0 x 10 m flat window thickness ... 

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