Transport or interface?

In single-particle impact measurements and in magneto-electrochemistry it has to be clarified whether an observed effect is due to mass transport or to processes at the interface. Which measured quantities separate the two contributions?

A magnetic field acts predominantly on transport via convection, but depending on the system can also influence the interface. The same question arises for the additional electric field in EFCE.

The independence of the control curve from the setpoint current points to an effect on the interfacial state, but does not rule out transport contributions. Impact measurements offer a separation: the event frequency is transport-controlled, while charge and shape of the individual transient are interface-controlled.

Impact events at a field-exposed microelectrode

1. Impact measurement of suitable nanoparticles at a microelectrode without additional field: reference values for frequency and charge per event.
2. The same measurement with a constant additional field in the EFCE geometry.
3. Control with a superimposed magnetic field at the EFCE cell: does the control curve change?

• Particle system and electrolyte have to be matched to 0.05 M H₂SO₄ and the gate geometry.
• The field electrode lies behind mica; whether the field in the electrolyte gap influences the particle trajectories remains to be estimated.
• Whether the external field reaches the interface has not been demonstrated (Debye length ≈ 1.2 nm).