It has long remained a challenge to push femtosecond dynamics towards the nanoscale and the level of individual molecules at ambient conditions. Here we face that challenge and first show that by controlling time and phase distribution of the optical excitation field to the dynamics of an individual molecule we can achieve a superior degree of control [1-3].Next we exploit the single-molecule coherent control to the energy transfer in pigment-protein antenna complexes in their dynamic natural environment. In these transfer processes, signatures of surprisingly long-lived coherences have emerged in 2-dimensional ensemble spectra of various light-harvesting complexes. Here our single molecule approach reveals ultrafast quantum coherent energy transfer within individual antenna complexes of a purple bacterium under physiological conditions. We find that quantum coherences between electronically coupled energy eigenstates persist at least 400 fs, and that distinct energy transfer pathways that change with time can be identified in each complex [4]. Our data suggest that longlived quantum coherence renders energy transfer in photosynthetic systems robust in the presence of disorder, which is a prerequisite for efficient light harvesting.   Clearly chemistry at the intersection of nanoscale and femtoseconds is showing great perspective.D.Brinks, F.D.Stefani, F.Kulzer, R.Hildner, et al., Nature 465  905 (2010)R.Hildner, D.Brinks, N.F. van Hulst, Nature Phys. 7  172 (2011)R.Hildner, D.Brinks, F.D.Stefani, N.F. van Hulst, PCCP 13  1888 (2011)R.Hildner, D.Brinks, J.B.Nieder, R.Cogdell, N.F. van Hulst, Submitted.

Femtosecond coherent control of single chromophores and photosynthetic complexes

246th National Meeting (2013)

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