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Absorption of a photon places a molecule in an excited state; the challenge is
in understanding the processes that occur subsequent to photoexcitation. One
way to investigate the excited states and dynamics of molecules on extremely
short timescales is with ultrafast spectroscopy. My research employs
femtosecond (fs) time-resolved absorption techniques in order to monitor the
excited state evolution of transition metal complexes. This involves studying
photoinduced charge separation, where examining the dynamics involved may lead
to a better understanding of the relationship between electron transfer and
excited-state relaxation to a state that is unable to transfer an electron.
One project I focus on involves the
use of time-resolved absorption anisotropy measurements to investigate how
solvation dynamics impact photo-induced charge-transfer in complexes such as
tris-(2,2’-bipyridine)ruthenium(II). This study aims to resolve a fundamentally
interesting question about the evolution of the excited state – whether the
excited electron is initially localized or delocalized. A second project
focuses on Fe2+-based sensitizers for use in dye-sensitized solar cells
(DSSCs). Despite the fact that iron-based sensitizers present new challenges
compared to more commonly employed ruthenium-based sensitizers, a better
understanding of the dynamics involved will hopefully lead to the development
of efficient, low cost dyes.
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