Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.


Carotenoid deactivation in an artificial light-harvesting complex via a vibrationally hot ground state

(full pdf)

Janne Savolainen, Tiago Buckup, Jürgen Hauer, Aliakbar Jafarpour, Carles Serrat, Marcus Motzkus and Jennifer L. Herek
Chemical Physics
Vol 357 Issues 1-3 p181-187 February 23, 2009

Ultrafast relaxation of a carotenoid in an artificial light-harvesting complex has been studied by transient absorption spectroscopy. The transient signal amplitudes at several wavelengths as well as the amplitudes of the underlying species associated spectra (SAS) are analysed for several excitation energies ranging over more than two orders of magnitude (10 nJ/pulse up to 3000 nJ/pulse). Our analysis shows that the contribution from the so-called S* signal on the long-wavelength side of the first allowed S0 → S2 transition has a markedly different excitation energy dependence and saturation behaviour than the electronic excited state S1. These observations are modelled and explained in terms of a two-photon excitation of a vibrationally hot ground state via an impulsive stimulated Raman scattering (ISRS). The experimental observations of the varying pulse energy dependencies of different excited state species are supported by an analysis based on a density-matrix formalism.
Printable version