Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules on a surface.
Abstract
Recent experiments have demonstrated that in a dense monolayer of photo-switchable
dye methyl-red molecules the relaxation of an initial birefringence follows a power-law
decay, typical for glass-like dynamics. The slow relaxation can efficiently be controlled
and accelerated by illuminating the monolayer with circularly polarized light, which
induces trans-cis isomerization cycles. To elucidate the microscopic mechanism, we
develop a two-dimensional molecular model in which the trans and cis isomers are represented
by straight and bent needles, respectively. As in the experimental system, the needles
are allowed to rotate and to form overlaps but they cannot translate. The out-of-equilibrium
rotational dynamics of the needles is generated using kinetic Monte Carlo simulations.
We demonstrate that, in a regime of high density and low temperature, the power-law
relaxation can be traced to the formation of spatio-temporal correlations in the rotational
dynamics, i.e., dynamic heterogeneity. We also show that the nearly isotropic cis
isomers can prevent dynamic heterogeneity from forming in the monolayer and that the
relaxation then becomes exponential.
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https://hdl.handle.net/10161/15336Published Version (Please cite this version)
10.1063/1.4943393Publication Info
Tavarone, Raffaele; Charbonneau, Patrick; & Stark, Holger (2016). Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules
on a surface. J Chem Phys, 144(10). pp. 104703. 10.1063/1.4943393. Retrieved from https://hdl.handle.net/10161/15336.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Patrick Charbonneau
Professor of Chemistry
Professor Charbonneau studies soft matter. His work combines theory and simulation
to understand the glass problem, protein crystallization, microphase formation, and colloidal
assembly in external fields.

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