Advertisement

Femtosecond to nanosecond relaxation time scales in electronically excited tetrakis(dimethylamino)ethylene: identification of the intermediates

  • B. Soep
  • J.M. Mestdagh
  • S. Sorgues
  • J.P. Visticot

Abstract:

In the TDMAE molecule (title molecule), the time evolution has been analyzed from the very initial excitation step down to a fluorescent state, over widely different time scales. Pump probe measurements have been performed at 3 different excitation wavelengths 400, 266 and 200 nm. The decay has been followed over the femtosecond and subnanosecond ranges with this method and the decay of the final charge transfer state has been detected by its fluorescence emission. This allows an overview of the complete decay mechanism. The initial relaxation pathway is interpreted in a similar way to ethylenic molecules, where the initial wavepacket is quickly trapped in a doubly excited state Z with charge transfer character. Then the Z state decays slowly (10-100 picoseconds) into the final state. In difference to monoalkenes the final stage of this evolution is a charge transfer state. The decay of transient Z state to the charge transfer state is a further assessment of the partial ionic character of the Z state. This type of molecule with low ionization potential can be viewed as a demonstrative example of the interrelation between the charge induced forces and the deformations in excited state reaction dynamics.

PACS. 33.50.-j Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion) – 34.30.+h Intramolecular energy transfer; intramolecular dynamics; dynamics of van der Waals molecules – 34.50.Gb Electronic excitation and ionization of molecules; intermediate molecular states (including lifetimes, state mixing, etc.) – 82.53.-k Femtochemistry 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© EDP Sciences, Springer-Verlag, Società Italiana di Fisica 2001

Authors and Affiliations

  • B. Soep
    • 1
  • J.M. Mestdagh
    • 1
  • S. Sorgues
    • 1
  • J.P. Visticot
    • 1
  1. 1.Laboratoire Francis Perrin, CEA/DRECAM/Service des Photons, Atomes et Molécules, C.E.N. Saclay, 91191 Gif-sur-Yvette Cedex, FranceFR

Personalised recommendations