Probe Beam Deflection Technique PBD

The probe beam deflection (PBD) technique (optical beam deflection or the mirage technique) is based on the measurement of refractive index gradients in front of the electrode I electrolyte interface [10,155,193,261-281]. 

The deflection of a laser beam aligned parallel to the electrode surface is measured. The beam deflection ( F) for a single flux, considering the concentration dependence of the refractive index, can be described by the following expression  

The probe laser beam is deflected towards the higher refraction index region. The direction of the deflection depends on the sign of the product The sign of  

The mass transport equations can be solved by taking into account the boundary conditions characteristic of the electrochemical technique applied. Furthermore, the flux should be calcirlated at a distance x because the center of the beam is at certain distance (typically 30-180 pm) from the electrode surface, so the PBD 

The respective equations for combined techniques are as follows. For PBD-chronoamperometry (potential step chronodeflectometry), 

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