Oliver Bixner,
Vladimir Lukes,
Tomas Mancal,
Juergen Hauer,
Franz Milota,
Michael Fischer,
Igor Pugliesi,
Maximilian Bradler, Walther Schmid,
Eberhard Riedle,
Harald F. Kauffmann,
Niklas Christensson
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ABSTRACT: The interaction of exciton and charge transfer (CT) states plays a central
role in photo-induced CT processes in chemistry, biology and physics. In this
work, we use a combination of two-dimensional electronic spectroscopy (2D-ES),
pump-probe measurements and quantum chemistry to investigate the ultrafast CT
dynamics in a lutetium bisphthalocyanine dimer in different oxidation states.
It is found that in the anionic form, the combination of strong CT-exciton
interaction and electronic asymmetry induced by a counter-ion enables CT
between the two macrocycles of the complex on a 30 fs timescale. Following
optical excitation, a chain of electron and hole transfer steps gives rise to
characteristic cross-peak dynamics in the electronic 2D spectra, and we monitor
how the excited state charge density ultimately localizes on the macrocycle
closest to the counter-ion within 100 fs. A comparison with the dynamics in the
radical species further elucidates how CT states modulate the electronic
structure and tune fs-reaction dynamics. Our experiments demonstrate the unique
capability of 2D-ES in combination with other methods to decipher ultrafast CT
dynamics.
The Journal of chemical physics 03/2012; 136(20). · 3.09 Impact Factor
