Excited-state processes in biomolecules

Photoresponsive biomolecules sense light through a chromophore, a prosthetic group,
deeply buried in the larger biomolecule. Photoabsorption promotes the chromophore to
an excited state, which could relax through multiple decay channels resulting in various
biophysical processes. Besides the major biological functions in the origin and function of
living systems, these biomolecules also serve as an excellent template in the field of optogenetic
tools for in vivo imaging of processes that occur deep inside tissues. Additionally,
these biomolecules find their application as biosensors allowing physiological control of
protein-protein interactions. Nevertheless, our understanding and ability to control the
excited-state processes of biomolecules are limited. Although experimental techniques
such as ultrafast spectroscopy help explore the excited-state dynamics of the chromophore,
the atomistic details behind the excited-state processes get buried behind the complicated
spectra. Therefore, the main motive of this thesis is to provide an atomistic interpretation
of spectra by detailing the mechanism behind the underlying biophysical processes. A
brief introduction to the biomolecules dealt with in this thesis is presented in chapter 1. In
addition, significant challenges in theoretical modeling of these excited-state processes in
biomolecules are also discussed.