The electron capture detector, reduction potential, electron transfer and photon methods of determining electron affinities are compared. The adiabatic electron affinities are (in eV): t-azobenzene(O-2), 1.578(5); t-azobenzene, 1378(5); cytosine, 1.043(5) from anion photoelectron spectra. The largest or ground state value for trans-azobenzene and an excited state electron affinity for cytosine, 0.70 eV are also determined by reduction potentials. Other excited state energies are (in eV): t-azobenzene, 0.328(5), 0.589(5), 0.690(5), 0.768(5), 0.954(5), 1.038(5), 1.150(5), 1.275(5) and cytosine, 0.089(5), 0.098(5), 0.198(5), 0.235(5). The cytosine values are consistent with electron transport and radiation damage and repair in DNA. (C) 2007 Elsevier B.V. All rights reserved.