Hannover 2010 – scientific programme

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SYQS: Symposium Quantum Control Spectroscopy

SYQS 1: Quantum Control Spectroscopy I

SYQS 1.2: Invited Talk

Thursday, March 11, 2010, 11:00–11:30, E 415

Quantum Control Spectroscopy: Understanding photobiology with coherently controlled matter waves — •Tiago Buckup^1,2, Jürgen Hauer³, Judith Voll⁴, Regina Vivie-Riedle⁴, and Marcus Motzkus^1,2 — ¹Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität, D-69120 Heidelberg, Germany. — ²Physikalische Chemie, Philipps-Universität, D-35043 Marburg, Germany. — ³Department of Physical Chemistry, University of Vienna, A-1090 Vienna, Austria. — ⁴Department Chemie, Ludwig-Maximilians-Universität, D-81377 München, Germany.

The combination of coherent control methods with time-resolved spectroscopy, namely Quantum Control Spectroscopy (QCS), is a compelling approach to disentangle ultrafast dynamics [1]. In particular, QCS can be very rewarding to investigate complex systems, such as light-harvesting complexes, where very often the traditional pump-probe spectroscopy fails. We report an experiment using phase-modulated degenerate four-wave mixing and provide a general mechanism for phase-only control of an open quantum system with an ultrashort excited state lifetime. We show by the use of coherent control that a low-frequency bending motion (178 cm⁻¹ in β-carotene) is the driving force behind the photophysically relevant step in carotenoids, a central constituent of many light harvesting complexes. We can now rationalize pulse shapes found in a whole class of quantum control experiments, ranging from simple dye molecules to embed-protein chromophores like all-trans-retinal in bacteriorhodopsin.

[1] Wohlleben, W. et al., ChemPhysChem 6 (2005) 850.