energy of activation

of an electrode reaction
https://doi.org/10.1351/goldbook.E02109
This is defined by the equation: \[U^{\ddagger } = -R\ T\ (\frac{\partial (\ln I_{0})}{\partial T^{-1}})_{p,c_{j},...}\] where \(I_{0}\) is the @[email protected] At any @[email protected] \(\eta \) it is defined by the equation: \[U^{\ddagger }\left(\eta \right) = -R\ (\frac{\partial (\ln (|I|))}{\partial T^{-1}})_{p,\eta ,c_{j},...}\] where \(I\) is the current passing from the electrode into the electrolyte.
Source:
PAC, 1974, 37, 499. (Electrochemical nomenclature) on page 516 [Terms] [Paper]