Picosecond Transient Absorption Spectra and the Twisted Intramolecular Charge Transfer Phenomenon |
| J. Dobkowski, Z.R. Grabowski, J. Jasny and Z. Zieliński Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warszawa, Poland |
| Received: April 24, 1995 |
| Dedicated to Professors Zdzisław Rusiewicz and Krzysztof Pigoń on the occasion of their 70th birthdays |
| Full Text PDF |
| An improved model of a computer-controlled picosecond absorption spectrometer was designed and constructed. Its operation is described, and applied to the measurement of transient spectra of p-N, N-dioctylamino-acetophenone. The spectroscopy and photophysics of this compound are compared to the other compounds exhibiting the dual fluorescence, assigned usually to the adiabatic formation of the "twisted" intramolecular charge transfer excited state. The data are discussed in relation to alternative suggestion of an inversion of the pyramidal amino nitrogen atom. The whole evidence supports the decoupling of the π-electronic systems of D+ and A- in the D+-A- polar excited state, in full accord with the "twisted" intramolecular charge transfer model. The peculiar behaviour of the long alkyl -NR2 derivatives (favouring the "twisted" intramolecular charge transfer state emission) seems to be primarily due to the decreasing oxidation potential of such electron donor groups. |
| DOI: 10.12693/APhysPolA.88.455 PACS numbers: 36.20.Kd, 06.60.In |