  By studying fluctuations in the electrostatic potential of a single electrode
immersed in a cold plasma, we were able to perform in situ electron
spectroscopy. Electron exchange processes that occur at the surface of the
electrode were triggered by the surface Auger process either using metastable
molecular nitrogen or triplet helium at ambient conditions. Ongoing redox
reactions were decomposed into their two fundamental half reactions and the
reduction and oxidation potentials were detected. We found that redox reactions
near the electrode surface are the result of binary interactions of a free
electron gas with a free hole gas that occur on a femtosecond time scale. The
measured lifetimes of electron-hole recombination processes and the elastic
scattering rate of the hole-hole process are in fair agreement with theoretical
estimates. The observed asymmetry in the energy distributions of free electron
and free hole ensembles suggests that at thermal equilibrium the identity of
hole differs from that of an electron vacancy.
