A global energy crisis is rapidly growing and consumption of limited energy resources (e.g.; fossil fuels) demands development of new sustainable energy resources. The remarkable efficiency of sunlight harvesting in natural photosynthesis has motivated researchers to study energy and charge transfer dynamics within photosynthetic pigment-protein complexes as well as their artificial analogs, shedding light on how to capture, store and utilize sunlight in most efficient and inexpensive way.
1. Following the introduction of expensive silicon-based solar cells utilized in spacecrafts in 1960's, low-cost dye-sensitized solar cells and organic/inorganic thin-film/bulk hetero-junction solar cells have been developed for past few decades. However the sensitivity of these inexpensive solar cells has so far been quite low (~10%) compared with natural light-harvesting systems. Using ultrafast two-dimensional coherent spectroscopy, we are interested in understanding energy and charge transfer dynamics within these novel synthetic complexes addressing crucial questions, for example: What are the dynamical bottle-necks in solar cells? and Does (quantum) coherence has any role in artificial analogs?.
2. The experimental observation of cross-peak beating in two-dimensional spectra of photosynthetic pigment-protein complexes have hinted the role of specific vibrational coherences mediated (and preserved) by the protein bath subsequent to coherent vibronic excitation of the chromophores i.e. the pigments. Using ultrafast pulse-shaping, we want to investigate the role of purely vibrational pre-excitation on subsequent energy and charge transfer dynamics in light-harvesting systems.
3. In order to fully understand the structure-function relationship during energy and charge transfer within light-harvesting networks, we need to spatiotemporally track dynamical events with ultrafast time-resolution and nano-scale space-resolution. Combining ultrafast fluorescence-detected coherent spectroscopy with super-resolution microscopy, we want to spatiotemporally follow energy and charge transfer dynamics.
- A. K. De, D. Monahan, J. M. Dawlaty and G. R. Fleming, "Two-dimensional Fluorescence-detected Coherent Spectroscopy with Absolute Phasing by Confocal Imaging of a Dynamic Grating and 27-step Phase-cycling", Journal of Chemical Physics, 194201 (1-8), 140, 2014.
- A. K. De, D. Roy and D. Goswami, "Selective Two-photon Fluorescence Suppression by Ultrafast Pulse-Pair Excitation: Control by Selective One-color Stimulated Emission", Journal of Biomedical Optics (Letters), 100505 (1-3), 16 (10), 2011. (Highlighted in Virtual Journal of Biological Physics, 22 (9), 2011.)
- A. K. De, D. Roy and Debabrata Goswami, "Fluorophore Discrimination by Tracing Quantum Interference in Fluorescence Microscopy", Physical Review A, 015402 (1-4), 83, 2011.
- A. K. De, D. Roy, A. Dutta and D. Goswami, "Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination", Applied Optics, G33-G37, 48 (31), 2009. (Highlighted in Virtual Journal for Biomedical Optics, 34 (2), 2009.)
- A. K. De and D Goswami, "Exploring the Nature of Photo-Damage in Two-Photon Excitation by Fluorescence Intensity Modulation", Journal of Fluorescence (Rapid Communication), 381-386, 19 (2), 2009.