Murrellrsquo;s localized orbital model is applied to indole, considered as composed of three fragments: benzene, ethylene, and a gsim;NH group. In addition to the usual locally excited and chargehyphen;transfer states, locally excited 3sand 3ppgr; Rydberg states of the gsim;NH group have been introduced and the mixed valencendash;Rydberg (3dpgr;) character of the locally excited state of the ethylene fragment considered. The model predicts a pure Rydberg 3slarr;1Atransition at 46 kK, polarized perpendicular to the molecular plane, which may explain the disappearance, in condensed media, of a shoulder (at 42.4 kK) present in the vapor phase absorption spectrum of indole. The 3dpgr; orbital confers a long range character to the1Laexcited state. Experiment unambiguously shows that rsquo;rsquo;exciplexrsquo;rsquo; formation of indoles with polar solvents occurs only if the emission originates from this state. Change, in polar media, from the Franckndash;Condon to a solvated Rydberg state, is therefore postulated.
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