Internal conversion in functionalized poly-chlorinated trityl radicals can be tuned by a characteristic high-frequency mode
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Updated: Oct 31, 2026

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Robert Toews1,2, Andreas Köhn1,2
1Institute for Theoretical Chemistry, University of Stuttgart, D-70569 Stuttgart, Germany. toews@theochem.uni-stuttgart.de.
Abstract:
We provide a theoretical analysis of trends in radiative losses by internal conversion (IC) in a series of doublet radical emitters and triplet diradicals derived from the poly-chlorinated trityl moiety. Minimizing radiative losses in these systems by molecular design is of current interest to opto-electronics and quantum technological approaches. Our results clearly indicate that IC in the doublet emitters as well as in different diradical architectures is governed by a characteristic high-frequency mode, which is associated with a quinoidal distortion. For the doublet emitters, we can establish that deliberate design allows to deactivate this mode as decay channel, resulting in a significantly reduced IC rate and an improved internal fluorescence quantum yield. We propose an analogous design principle for highly fluorescent triplet diradicals, and discuss the role of a high fluorescence efficiency in the context of quantum applications.
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