Photophysics and photochemistry of organic chromophores are extremely interesting, complex and challenging due to the involvement of several close-lying electronic states and
nonadiabatic couplings between them. Here, my focus is on the computational exploration of photophysics and photochemistry of two important organic chromophores namely fluorescein and indole. [1-4] Regarding this, I will systematically address a few important questions i.e. (1) why does fluorescein chromophore show no fluorescence in the gas phase but has high fluorescence quantum yield in water ? (2) What is the effect of electronic substitution on the ground and excited state properties of the indole chromophore ? Is the time dependent density functional theory (TDDFT) method adequate to describe the excited states of indole and indole derivatives? (3) What is the time scale, quantum yield and underlying mechanism of photodissociation dynamics of indole? What is the role of nonadiabatic coupling on these parameters? These questions are answered from computational studies using excited state electronic structure calculations and non-adiabatic quantum dynamics.

References
[1] A. Roy, S. Samanta, S. Roy, S. S. Kumar and P. Mondal, J. Chem. Phys. (2024) 160, 034302.
[2] S. Ray and P. Mondal, ChemPhysChem (2023), 24, e202200541.
[3] S. Ray, D. Koner and P. Mondal, Electron. Struct., (2023), 5, 013001.
[4] S. Ray, S. Sasmal, P. Mondal, J. Chem. Phys. (2025), 163, 144310