The main focus of our research is to explore a wide range of problems in condensed phase chemical dynamics through a combination of theory and experiment.
I) Ultrafast spectroscopy
Apart from routine picosecond fluorescence lifetime and femtosecond pump-probe (transient absorption) measurements, we have constructed a Two-dimensional electronic spectroscopy (2DES) set-up (using an AOPDF pulse shaper) and, quite recently, a Time-Resolved Impulsive Stimulated Raman Spectroscopy (TR-ISRS) set-up. This has enabled us to study:
1) Energy/charge transfer dynamics within
i) Multichromophoric systems
ii) Photovoltaic materials (quantum dots, perovskites)
iii) Fluorescent proteins
2) Early-time (<1 ps) solvation dynamics
3) Dynamics of optically "dark" states
II) Optical trapping:
We have designed and built a versatile Optical Tweezer (OT) set-up having multimodal detection capabilities. Under femsosecond pulsed excitation, this has enabled us to study:
1) Non-linear optical effects in optical trapping of:
i) Dielectric spherical particles with high Kerr nonlinearity
ii) Metallic nanoparticles under excitation near plasmon resonance
The Optical Tweezer set-up will be coupled with a Laser Beam Shaping set-up (using a 2D LC-SLM) to build a Holographic Optical Tweezer (HOT) set-up. This will enable us to study:
2) Long-range interaction between trapped particles in an array leading to emergence of collective phenomena
To better understand the fine balance between nonlinear optical and thermal nonlinearities, we have also started experiments on:
3) Photo-thermal spectroscopy
Along with experiment, we also perform extensive numerical simulation for:
1) Estimating nonlinear force/potential in femtosecond laser trapping
2) Modelling excited state dynamics
We also use software packages (Gaussian 09) for routine electronic structure theory calculation.
- Anita Devi and Arijit K. De, Theoretical investigation on nonlinear optical effects in laser trapping of dielectric nanoparticles with ultrafast pulsed excitation, Optics Express, 21485-21496, 24 (9), 2016.
- Anita Devi and Arijit K. De, Theoretical estimation of nonlinear optical force on dielectric spherical particles of arbitrary size under femtosecond pulsed excitation, Physical Review A, 023856 (1-9), 96 (2), 2017.
- Yogita Silori, Shivalee Dey and Arijit K. De, How to study picosecond solvation dynamics using fluorescent probes with small Stokes shifts, Chemical Physics Letters, 222-226, 693, 2018. "Frontiers Article", Cover page article.
- Shaina Dhamija, Bhisham Thakur, Purnananda Guptasarma and Arijit K. De, Probing excited state dynamics of Venus: origin of dual-emission in fluorescent proteins, Faraday Discussions, 39-54, 207, 2018.
- Meghanad Kayanattil and Arijit K. De, Theoretical estimation of optimal parameters for maximum fluorescence under pulsed excitation, ChemPhysChem, 2796-2803, 19, 2018.
- Yogita Silori and Arijit K. De, Tuning effect of local environment to control mechanism of fluorescence depolarization: Rotational diffusion VS resonance energy transfer within homoaggregates of xanthenes, Journal of Photochemistry and Photobiology A: Chemistry, 198-206, 377, 2019.
- Yogita Silori, Pankaj Seliya and Arijit K. De, Early time solvation dynamics probed by spectrally resolved degenerate pump-probe spectroscopy, ChemPhysChem, 1488-1496, 20 (11), 2019.