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Probing chirality fluctuations in molecules by nonlinear optical spectroscopy.

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Geometric fluctuations enable forbidden processes. For a perylene bisimide dyad, these fluctuations induce finite energy transfer and chiral optical signals, revealing correlation times through waiting time dependence.

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Area of Science:

  • Physical Chemistry
  • Spectroscopy
  • Materials Science

Background:

  • Symmetry breaking, driven by geometric fluctuations, can activate normally forbidden processes.
  • Förster-type energy transfer is forbidden in perylene bisimide dyads at equilibrium due to perpendicular dipole moments.

Purpose of the Study:

  • To demonstrate an analogous effect of geometric fluctuations on chirality symmetry breaking.
  • To investigate the induction of finite 2D chiral optical signals from non-chiral equilibrium geometries.
  • To explore the experimental revelation of fluctuation correlation times.

Main Methods:

  • Theoretical investigation of a perylene bisimide dyad system.
  • Analysis of energy transfer and chiral optical response under geometric fluctuations.
  • Examination of the waiting time dependence of 2D chiral signals.

Main Results:

  • Geometric fluctuations induce finite energy transfer, dependent on dipole variance.
  • Fluctuations enable finite 2D chiral optical signals from a non-chiral dimer.
  • The correlation time of geometric fluctuations can be determined from the waiting time dependence of the 2D signal.

Conclusions:

  • Geometric fluctuations play a crucial role in enabling forbidden optical phenomena like energy transfer and chiral responses.
  • The study highlights a novel pathway for generating chiral signals from achiral molecules.
  • This work provides a method for experimentally probing molecular dynamics through optical spectroscopy.