Flexible cell designs for simultaneous electrochemical electron spin resonance measurements with a coaxial microwave cavity

New cell designs of coaxial microwave cavity type are reported for simultan eous electrochemical electron spin resonance measurements. Adjustable metal lic shields are introduced so that the working electrode can be much shorte r than the full height of the cavity. Besides the traditional helical elect rode, the working electrode can be cylinders made from metallic plates, mes hes, or even composite materials. The counter electrode can be placed eithe r inside or outside the cavity. These features make the new designs more fl exible than those previously reported. The impacts of eddy currents due to the magnetic-field modulation are examined and discussed. With a nonperfora ted cylindrical electrode, this cell can be used to determine the standard potential and the number of electrons transferred in electrode reactions in volving radicals. Other possible applications are also briefed. (C) 2000 Am erican Institute of Physics. [S0034-6748(00)01410-6].