The processes of interest occur very fast (10-15-10-10sec). These events are
triggered by the absorption of energy from a laser pulse. After excitation, the
systems can undergo several changes, involving redistribution of the energy,
lose of coherence, formation of intermediates, etc. The evolution of those
changes provides useful information to understand the light-matter interactions.
Since the temporal evolutions are extremely fast, it is necessary to probe the
system in time-scales faster that the times it takes them to evolve.
In general, ultrafast spectroscopy techniques involve an initial step
(excitation by a short laser pulse) followed by the probing of the evolution of
an optical transition (through absorption, scattering or photoluminescence) . To
probe the evolution of a fast process we utilize techniques equivalent to the
stroboscopic method develop by Harold “Doc” Edgerton.
In our experiments, as the system is evolving in time we collect snapshots of
a chosen property, modulated by the initial absorption of energy. For example,
at t=0, a conjugated polymer is excited with visible or UV light, After that
triggering event, the energy is transferred to low lying energy levels of the
polymer or to a quencher/acceptor. By monitoring the time evolution of the
polymer fluorescence together with the time-evolution of the acceptor’s
fluorescence, we can build a set of snapshot describing the energy transfer
process.
These programs are inherently interdisciplinary with involvement
from physical chemists, materials scientists, and synthetic chemists. If you are
interested on learning more about our work, please contact me directly at kleiman@chem.ufl.edu.
These programs are inherently interdisciplinary with involvement
from physical chemists, materials scientists, and synthetic chemists. If you are
interested on learning more about our work, please contact me directly at kleiman@chem.ufl.edu.