A further item to note is that compounds with electronegative E atoms (primarily O) which are weakly aromatic or nonaromatic in S0, gain some aromaticity in the MCIcomponent in the n,* state (i.e., they obtain values that are more than half of that in S0). These species have rather localized -electrons in S0 because of the highly electronegative and electron deficient O + . Upon excitation to the n,* state, the delocalization of the -electrons increases due to the addition of one electron to the -system, and the -component of MCI increases (see Figures and).