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.

 

Single-molecule pump-probe experiments reveal variations in ultrafast energy redistribution

(full pdf)

E.M.H.P. van Dijk, J. Hernando, M.F. García-Parajó, and N.F. van Hulst
the journal of Chemical Physics
vol. 123 issue 6 p064703 may 2 2005

Single-molecule pump probe (SM2P) is a novel, fluorescence-based technique that allows the study of ultrafast processes on the single-molecule level. Exploiting SM2P we have observed large variations (from 1  ps to below 100  fs) in the energy redistribution times of chemically identical molecules in the same sample. Embedding the molecules in a different matrix or changing the excitation wavelength does not lead to significant changes in the average redistribution time. However, chemically different molecules exhibit different characteristic redistribution times. We therefore conclude that the process measured with the SM2P technique is dominated by intramolecular energy redistribution and not intermolecular transfer to the surrounding matrix. The matrix though is responsible for inducing conformational changes in the molecule, which affect the coupling between electronic and vibrational modes. These conformational changes are the main origin of the observed broad distribution of redistribution times. ©2005 American Institute of Physics
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