München 2004 – scientific programme

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MO: Molekülphysik

MO 4: Femtosekundenspektroskopie: Elektrontransfer

MO 4.4: Talk

Monday, March 22, 2004, 11:45–12:00, HS 315

Experimental verification of the ultrafast intramolecular electron transfer in triphenylmethane lactones — •Tanja Bizjak¹, Jerzy Karpiuk², Stefan Lochbrunner¹, and Eberhard Riedle¹ — ¹LS für BioMolekulare Optik, Sektion Physik, Ludwig-Maximilians-Universität München — ²Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw

A search for and the exploration of donor-acceptor systems with high electron transfer rates is very important both for practical reasons and for deeper understanding of the various factors controlling charge transfer processes that occur on the time scale comparable to vibrational relaxation and even electronic dephasing. It has been recently estimated that the photoinduced charge separation (CS) process in malachite green lactone proceeds within t≤130 fs [1]. In the present study the kinetics of CS in malachite green lactone and in phenolphthalein in aprotic and protic media have been explored using fs transient absorption spectroscopy with 270 nm excitation. It has been found that in malachite green lactone in acetonitrile both the S₂→S₁ electronic relaxation and the CS process are completed within 130-150 fs. The phenol cation radical, a product of the primary CS in phenolphthalein in acetonitrile excited directly to S₁ state, appears in transient absorption spectra with a rise time of 55 fs, the fastest CS time reported so far for organic donor-acceptor systems.

[1] J. Karpiuk, Phys. Chem. Chem. Phys. 5 (2003) 1078.