Ultrafast photo-induced charge transfer unveiled by two-dimensional electronic spectroscopy

作者：Bixner Oliver^*; Lukes Vladimir; Mancal Tomas; Hauer Juergen; Milota Franz; Fischer Michael; Pugliesi Igor; Bradler Maximilian; Schmid Walther; Riedle Eberhard; Kauffmann Harald F; Christensson Niklas

来源：Journal of Chemical Physics, 2012, 136(20): 204503.

DOI：10.1063/1.4720492

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.

• 出版日期2012-5-28