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Experimental evidence for dissociative intramolecular charge transfer processes is found for gas-phase ferrocene-aniline derivatives after local ionization at the aniline chromophore site via intermediate states with predominant aniline character. The direct ionization at the ferrocene site can be excluded since there is a rapid dissociation of ferrocene in the intermediate state prior to ionization so that no ferrocene ions would be produced in this case. Because of the higher local ionization energy of the chromophore, charge transfer takes place after local ionization. The released energy and additional photon absorption leads to breaking of bonds and results in a dissociation into intact ferrocene or ferrocene-containing cations and neutral fragments.

The feasibility of using the vibrational Stark effect for the observation of charge transfer reactions on a short time scale is demonstrated. The photoinduced oxidation of ferrocenophanone induces a fast shift of the carbonyl stretching frequency which is observable by femtosecond time-resolved IR spectroscopy. The observed shift is in good agreement with the IR spectrum of chemically oxidized ferrocenophanone and with theoretical predictions based on vibrational Stark effect calculations. The time dependence of the signal mirrors the charge transfer dynamics on the fs to ps time scale, as observed by optical spectroscopy. This shows that the vibrational Stark effect provides access to observing charge transfer reactions in the IR on the fs time scale. Since the Stark effect is sensitive to changes of the electric field alone, the sensor bond does not need to be part of the molecular system under investigation, but may be a noninvolved “spectator” bond located in its immediate surroundings.

Comparison of the ultrafast electron transfer kinetics of a solute-solvent, system and its intramolecular analogue shows that the large solvent to solute rates are intrinsic and not due to accumulation of reaction probabilities.

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