Assistant Professor
BS/MS IIT Kanpur
Ph.D. Chemical Physics,
University of Colorado, Boulder
Welcome to Multidimensional Spectroscopy and Imaging Group  [‘musig‘]

Gaining a fundamental understanding of the quantum dynamics of energy and charge transfer is key for any scalable energy harvesting and storage technology. Such technologies depend on materials such as organic polymers and singlet fission materials, inorganic perovskites, quantum dots and layered 2D materials. Femtosecond timescales and nanometer lengthscales are the natural scales to probe the initial steps of energy and charge transfer phenomenon that governs the performance of these technologies. Key design principles, such as exploiting quantum coherence or vibronic mixing to enhance function in artificial light-harvesting systems, could also be learned by probing the quantum dynamics of light-harvesting in natural photosynthetic proteins.

Our group develops state-of-the-art spectroscopic techniques and quantum dynamical models to understand questions such as how does an exciton dissociate to yield charge carriers, why is this yield efficient in certain materials versus poor in others, why do natural photosynthetic proteins have near unity quantum efficiency of charge carrier generation, can coupled vibrational-electronic motions enhance energy and charge transfer, etc. We are also interested in applied aspects of spectroscopy such as inventing better sensing, imaging and diagnostic tools. 

Please go over our recent publications for a flavor of the kind of experimental and theoretical work carried out in the group. Visit our homepage or our laboratory to know more about our current directions. If you are interested in the same questions as we are, please email me your CV along with your research interests.

  1. Asha S. Thomas*, Vivek N. Bhat*, and Vivek Tiwari, “Rapid scan white light two-dimensional electronic spectroscopy with 100 kHz shot-to-shot detection”,  J. Chem. Phys. (2023), 159, 244202. link (*denotes equal authors). Feature Article (top 3% papers in the field selected by the editors). Patents IPO/202241074681 and PCT/IN2023/050664
  2. Atandrita Bhattacharyya, Amitav Sahu, Sanjoy Patra, and Vivek Tiwari, “Low- and high-frequency vibrations synergistically enhance singlet exciton fission through robust vibronic resonances”,  Proc. Natl. Acad. Sci. USA (2023), 120 (49), e2310124120. link. Read IISc Press release hereBeats That Matter
  3. Amitav Sahu and Vivek Tiwari, “Vibrations That Do Not Promote Vibronic Coupling Can Dominate Observed Lineshapes in Two-Dimensional Electronic Spectroscopy“, J. Phys. Chem. Lett. (2023), 14, 4617.
  4. Vivek N Bhat*, Asha S Thomas*, Atandrita Bhattacharyya and Vivek Tiwari, “Rapid scan white light pump–probe spectroscopy with 100 kHz shot-to-shot detection”,  OSA Optics Continuum (2023), 2, 1981. link (*denotes equal authors)
  5. Amitav Sahu, Vivek Bhat, Sanjoy Patra, and Vivek Tiwari, “High-sensitivity Fluorescence-Detected Multidimensional Electronic Spectroscopy Through Continuous Pump-probe Delay Scan”,  J. Chem. Phys. (2023), 158, 024201. link
  6. Sanjoy Patra and Vivek Tiwari, “Vibronic Resonance Along Effective Modes Mediates Selective Energy Transfer in Excitonically Coupled Aggregates“, J. Chem. Phys. (2022), 156, 184115. link
  7. Vivek Tiwari, “Multidimensional electronic spectroscopy in high-definition—Combining spectral, temporal, and spatial resolutions“, J. Chem. Phys. (2021), 154, 230901. JCP Most Read Perspectives 2021 link.
  8. Sanjoy Patra, Amitav Sahu, and Vivek Tiwari, “Effective Normal Modes Identify Vibrational Motions which Maximally Promote Vibronic Mixing in Excitonically Coupled Aggregates”, J. Chem. Phys. Communication (2021), 154, 111106. link
  9. Amitav Sahu, Jo Sony Kurian and Vivek Tiwari, “Vibronic Resonance is Inadequately Described by One-particle Basis Sets“, J. Chem. Phys. (2020), 153, 224114. Feature Article (top 3% papers in the field selected by the editors). link
  10. Abhisek A. Mohapatra, Vivek Tiwari* and Satish A. Patil*, “Energy transfer in ternary blend organic solar cells: recent insights and future directions“, Energy and Environmental Science (2021), 14, 302. Perspective Article (* denotes corresponding authors).