Rahul Kumar Gupta

IIT Kanpur

Education / Work History

  • Ph.D. Scholar, IIT Kanpur (2013-present)
  • M.Sc, University of Delhi (2008-2010)
  • B.Sc, Deshbandhu College Delhi (2008)

Research Topic / Interest

My main interest is currently:

  • Thermal Lens Microscopy

Publications

These include only those published in our lab.

  1. Organic-Inorganic Hybrid Halide Perovskites Impregnated with Group 1 and 15 Elements for Solar Cell Application. P. Dey, H. Singh, R. K. Gupta, D. Goswami, and T. Maiti, Journal of Physics and Chemistry of Solids 144, 109518 (2020) [Abstract] [PDF] [BibTeX]

    Abstract: In this report, we explored the substitution of triple cations at B-site of ABX3 perovskite architecture in inorganic-organic hybrid perovskite materials in order to improve its stability over moisture and heat, which is considered as the paramount obstacles for commercialization of perovskite solar cell. In the current investigation we synthesized two novel perovskite materials, Methylammonium potassium bismuth lead iodide [CH3NH3K0.25Bi0.25Pb0.5I3] (MKBPI) and Methylammonium sodium bismuth lead iodide [CH3NH3Na0.25Bi0.25Pb0.5I3] (MNBPI). XRD studies confirmed hexagonal crystal structure with P63/mmc space group for both the perovskites. Antisolvent treatment improved the surface coverage and morphology of the thin films, observed in FESEM. UV–Vis spectra demonstrated high absorption coefficient. Band gap was estimated as 2.09 eV for MKBPI. Fluorescence decay kinetics study revealed charge carrier lifetime on the order of nano second. DSC and TGA measurements confirmed thermal stability of these perovskites up to 280 °C. Further, we carried out detailed degradation study using XRD and UV–Vis spectroscopy of these perovskite thin films kept at ambient atmosphere for two weeks. Remarkably thin films of these perovskites exhibited good absorption even after 14 days.

     BibTeX: @article{deyOrganicinorganicHybridHalide2020,
  title = {Organic-Inorganic Hybrid Halide Perovskites Impregnated with {{Group}} 1 and 15 Elements for Solar Cell Application},
  author = {Dey, Pritam and Singh, Harish and Gupta, Rahul K. and Goswami, Debabrata and Maiti, Tanmoy},
  date = {2020-09-01},
  journaltitle = {Journal of Physics and Chemistry of Solids},
  shortjournal = {Journal of Physics and Chemistry of Solids},
  volume = {144},
  pages = {109518},
  issn = {0022-3697},
  doi = {10.1016/j.jpcs.2020.109518},
  url = {http://www.sciencedirect.com/science/article/pii/S0022369719327763},
  urldate = {2020-07-11}
}
  2. Exploring the Effects of Intermolecular Interactions on the Self-Defocusing of Binary Liquid Mixtures Using Single Beam z-Scan Technique - Asian Journal of Physics. R. K. Gupta, S. Kant, and D. Goswami, Asian Journal of Physics 31, 897–904 (2023) [Abstract] [PDF] [BibTeX]

    Abstract: Self-defocusing (or negative lens effect) study of different sets of binary liquid mixtures having varying polarities has been carried out by employing a high repetition rate (HRR) femtosecond pulsed laser and utilising a single beam close aperture z-scan (CAZS) technique. We determined the change in transmittance values between peak and valley (ΔTp-v) of the CAZS trace for each different binary liquid mixtures at the varying composition of components. We correlated the variation of ΔTp-v values with the composition ratio of components to the change in physical parameters, which in turn affects the intermolecular interactions. Here, the combined effects of polarity differences and different molecular structures having steric hindrance are found to affect intermolecular interactions significantly in binary mixtures which in turn affect the self-defocusing effect.

     BibTeX: @article{guptaExploringEffectsIntermolecular2023,
  title = {Exploring the Effects of Intermolecular Interactions on the Self-Defocusing of Binary Liquid Mixtures Using Single Beam z-Scan Technique - {{Asian Journal}} of {{Physics}}},
  author = {Gupta, Rahul K. and Kant, Surya and Goswami, Debabrata},
  date = {2023-02-20},
  journaltitle = {Asian Journal of Physics},
  volume = {31},
  pages = {897--904},
  url = {https://asianjournalofphysics.com/exploring-the-effects-of-intermolecular-interactions-on-the-self-defocusing-of-binary-liquid-mixtures-using-single-beam-z-scan-technique/},
  urldate = {2023-07-28}
}
  3. Investigating the Effects of Intermolecular Interactions on Nonlinear Optical Properties of Binary Mixtures with High Repetition Rate Femtosecond Laser Pulses. R. K. Gupta, S. Verma, S. Singhal, S. Kant, and D. Goswami, PeerJ Physical Chemistry 4, e23 (2022) [Abstract] [PDF] [BibTeX]

    Abstract: Measurements of nonlinear optical (NLO) properties of different binary mixtures having carbon disulfide (CS2) as the common component, namely CS2-acetone, CS2-cyclopentanone, CS2-toluene, and CS2-carbon tetrachloride (CCl4), are carried out by using the z-scan technique. Open-aperture z-scan (OAZS) and close-aperture z-scan (CAZS) experiments are performed to determine the nonlinear absorption coefficient (β) and nonlinear refractive index (n2) of all binary liquid mixtures at various compositions of the components by employing a pulsed, high repetition rate (HRR) femtosecond laser. Also, we were able to use the flowing liquid to measure NLO properties in the CS2-acetone binary mixture to remove the cumulative thermal effects produced due to the pulsed HRR laser light. Nonlinear refractive index (n2) values are found to be influenced by the weak dipole-induced dipole intermolecular interactions between the nonpolar CS2 and polar acetone as well as cyclopentanone of the respective binary mixtures. On the contrary n2 values are not found to be affected by the intermolecular interactions in CS2-toluene and CS2-CCl4 binary mixtures. In comparison, the nonlinear absorption coefficient (β) values are not found to be affected by the same in all different sets of binary mixtures.

     BibTeX: @article{guptaInvestigatingEffectsIntermolecular2022,
  title = {Investigating the Effects of Intermolecular Interactions on Nonlinear Optical Properties of Binary Mixtures with High Repetition Rate Femtosecond Laser Pulses},
  author = {Gupta, Rahul Kumar and Verma, Sachin and Singhal, Sumit and Kant, Surya and Goswami, Debabrata},
  date = {2022-06-07},
  journaltitle = {PeerJ Physical Chemistry},
  shortjournal = {PeerJ Phy. Chem.},
  volume = {4},
  pages = {e23},
  publisher = {{PeerJ Inc.}},
  issn = {2689-7733},
  doi = {10.7717/peerj-pchem.23},
  url = {https://peerj.com/articles/pchem-23},
  urldate = {2022-12-31}
}
  4. Two-Photon-Induced Fluorescence Study of Rhodamine-6G Dye in Different Sets of Binary Solvents. R. K. Gupta, S. Kant, A. K. Rawat, and D. Goswami, Journal of Fluorescence (2020) [Abstract] [PDF] [BibTeX]

    Abstract: This study deals with the effects of different sets of binary solvents on the Two-Photon Induced Fluorescence (TPIF), a non-linear process, of the Rhodamine-6G (Rh6G) dye, which is a well-known xanthene dye. This work examines the importance of inter-molecular interactions, which results in the modulation of the TPIF of the Rh6G. In this work, we have investigated three binary solvent mixtures representing varying polarity and intermolecular interactions. Specific solvent mixtures used are methanol-water, methanol-dimethyl formamide, and methanol-chloroform. Since the solvent polarity across these binary solvents differs, there are significant intermolecular interactions in the binary mixture solvents, which modulate the two-photon process of Rh6G when irradiated with high-intensity laser light at 780 nm. In our studies, we find that Rh6G in the MeOH-H2O binary solvent has maximum red-shift and minimum intensity as compared to other pairs of binary liquids when the volume fraction of methanol decreases due to more extensive hydrogen bonding between the two components. Additionally, at 1:1 ratio of binary mixtures, Rh6G is found to have the highest TPEACS value for methanol-chloroform binary solvent and reason for that is related to the formation of weak H-bond networks between proton donor chloroform and proton acceptor methanol.

     BibTeX: @article{guptaTwoPhotonInducedFluorescenceStudy2020,
  ids = {guptaTwoPhotonInducedFluorescenceStudy2020a},
  title = {Two-{{Photon-Induced Fluorescence Study}} of {{Rhodamine-6G Dye}} in {{Different Sets}} of {{Binary Solvents}}},
  author = {Gupta, Rahul Kumar and Kant, Surya and Rawat, Ashwini Kumar and Goswami, Debabrata},
  date = {2020-07-01},
  journaltitle = {Journal of Fluorescence},
  shortjournal = {J Fluoresc},
  issn = {1573-4994},
  doi = {10.1007/s10895-020-02577-0},
  url = {10.1007/s10895-020-02577-0},
  urldate = {2020-07-11}
}
  5. White Light Induced E/Z-Photoisomerization of Diphenylamine-Tethered Fluorescent Stilbene Derivatives: Synthesis, Photophysical, and Electrochemical Investigation. S. Mishra, P. Awasthi, J. Singh, R. K. Gupta, V. Singh, R. Kant, R. Jeet, D. Goswami, and A. Goel, The Journal of Organic Chemistry 83(7), 3669–3678 (2018) [Abstract] [PDF] [BibTeX]

    Abstract: A facile synthesis and detailed photophysical investigation of E/Z-isomerization of fluorescent diphenylamine tethered stilbene derivatives (DPASs) under white light exposure have been carried out to understand the effect on fluorescence, electrochemical properties, and photostability under various activation/deactivation pathways. In solution state, in the dark, the E-isomer of DPASs (6a−d) exhibited high fluorescence quantum yields (Φfl ≈ 53% to 60% in DMSO). However, on white light exposure, 1H NMR and HPLC studies revealed that pure E-isomer of the DPAS 6a (∼9.5 mM) started converting into its Z-form by photoisomerization until it reaches to nearly equilibrium. At low concentrations (∼10 μM), the absorption band of the pure Eisomer in the range of 350−450 nm gradually decreased to adopt Z-conformation 6a′ until a photostationary state was reached. The structure of the E-isomer 6a was unequivocally confirmed by X-ray diffraction analysis. The synthesized DPAS compounds 6a−d possessed positive solvatochromic properties, two photon absorption properties, and good thermal stability. The electrochemical investigations using DPASs showed reversible oxidation resulting in formation of a stable radical cation. Owing to useful photophysical, electrochemical and thermal properties, these DPAS derivatives are suitable for their application in biomedical imaging as well as in fabrication of electroluminescent materials.

     BibTeX: @article{mishraWhiteLightInduced2018,
  title = {White {{Light Induced E}}/{{Z-Photoisomerization}} of {{Diphenylamine-Tethered Fluorescent Stilbene Derivatives}}: {{Synthesis}}, {{Photophysical}}, and {{Electrochemical Investigation}}},
  shorttitle = {White {{Light Induced E}}/{{Z-Photoisomerization}} of {{Diphenylamine-Tethered Fluorescent Stilbene Derivatives}}},
  author = {Mishra, Shachi and Awasthi, Pallavi and Singh, Jagriti and Gupta, Rahul Kumar and Singh, Vikram and Kant, Ruchir and Jeet, Ram and Goswami, Debabrata and Goel, Atul},
  date = {2018-04-06},
  journaltitle = {The Journal of Organic Chemistry},
  shortjournal = {J. Org. Chem.},
  volume = {83},
  number = {7},
  pages = {3669--3678},
  issn = {0022-3263, 1520-6904},
  doi = {10/gc6tzq},
  url = {http://pubs.acs.org/doi/10.1021/acs.joc.8b00033},
  urldate = {2019-08-01}
}
  6. Deciphering Micro-Polarity inside the Endoplasmic Reticulum Using a Two-Photon Active Solvatofluorochromic Probe. K. Pal, I. Samanta, R. Kumar Gupta, D. Goswami, and A. Lal Koner, Chemical Communications 54(75), 10590–10593 (2018) [PDF] [BibTeX] 
     BibTeX: @article{palDecipheringMicropolarityEndoplasmic2018,
  title = {Deciphering Micro-Polarity inside the Endoplasmic Reticulum Using a Two-Photon Active Solvatofluorochromic Probe},
  author = {Pal, Kaushik and Samanta, Indranil and Kumar~Gupta, Rahul and Goswami, Debabrata and Lal~Koner, Apurba},
  date = {2018},
  journaltitle = {Chemical Communications},
  volume = {54},
  number = {75},
  pages = {10590--10593},
  doi = {10/gf5mqx},
  url = {https://pubs.rsc.org/en/content/articlelanding/2018/cc/c8cc03962c},
  urldate = {2019-08-01}
}
  7. Deciphering Micro-Polarity inside the Endoplasmic Reticulum Using a Two-Photon Active Solvatofluorochromic Probe. K. Pal, I. Samanta, R. Kumar Gupta, D. Goswami, and A. Lal Koner, Chemical Communications 54(75), 10590–10593 (2018) [PDF] [BibTeX] 
     BibTeX: @article{palDecipheringMicropolarityEndoplasmic2019,
  langid = {english},
  title = {Deciphering Micro-Polarity inside the Endoplasmic Reticulum Using a Two-Photon Active Solvatofluorochromic Probe},
  volume = {54},
  url = {https://pubs.rsc.org/en/content/articlelanding/2018/cc/c8cc03962c},
  doi = {10/gf5mqx},
  number = {75},
  journaltitle = {Chemical Communications},
  urldate = {2019-08-01},
  date = {2018},
  pages = {10590-10593},
  author = {Pal, Kaushik and Samanta, Indranil and Kumar Gupta, Rahul and Goswami, Debabrata and Lal Koner, Apurba}
}
  8. White Light Induced E/Z-Photoisomerization of Diphenylamine-Tethered Fluorescent Stilbene Derivatives: Synthesis, Photophysical, and Electrochemical Investigation. S. Mishra, P. Awasthi, J. Singh, R. K. Gupta, V. Singh, R. Kant, R. Jeet, D. Goswami, and A. Goel, J. Org. Chem. 83(7), 3669–3678 (2018) [Abstract] [PDF] [BibTeX]

    Abstract: A facile synthesis and detailed photophysical investigation of E/Z-isomerization of fluorescent diphenylamine tethered stilbene derivatives (DPASs) under white light exposure have been carried out to understand the effect on fluorescence, electrochemical properties, and photostability under various activation/deactivation pathways. In solution state, in the dark, the E-isomer of DPASs (6a−d) exhibited high fluorescence quantum yields (Φfl ≈ 53% to 60% in DMSO). However, on white light exposure, 1H NMR and HPLC studies revealed that pure E-isomer of the DPAS 6a (∼9.5 mM) started converting into its Z-form by photoisomerization until it reaches to nearly equilibrium. At low concentrations (∼10 μM), the absorption band of the pure Eisomer in the range of 350−450 nm gradually decreased to adopt Z-conformation 6a′ until a photostationary state was reached. The structure of the E-isomer 6a was unequivocally confirmed by X-ray diffraction analysis. The synthesized DPAS compounds 6a−d possessed positive solvatochromic properties, two photon absorption properties, and good thermal stability. The electrochemical investigations using DPASs showed reversible oxidation resulting in formation of a stable radical cation. Owing to useful photophysical, electrochemical and thermal properties, these DPAS derivatives are suitable for their application in biomedical imaging as well as in fabrication of electroluminescent materials.

     BibTeX: @article{mishraWhiteLightInduced2019,
  langid = {english},
  title = {White {{Light Induced E}}/{{Z}}-{{Photoisomerization}} of {{Diphenylamine}}-{{Tethered Fluorescent Stilbene Derivatives}}: {{Synthesis}}, {{Photophysical}}, and {{Electrochemical Investigation}}},
  volume = {83},
  issn = {0022-3263, 1520-6904},
  url = {http://pubs.acs.org/doi/10.1021/acs.joc.8b00033},
  doi = {10/gc6tzq},
  shorttitle = {White {{Light Induced E}}/{{Z}}-{{Photoisomerization}} of {{Diphenylamine}}-{{Tethered Fluorescent Stilbene Derivatives}}},
  number = {7},
  journaltitle = {J. Org. Chem.},
  urldate = {2019-08-01},
  date = {2018-04-06},
  pages = {3669-3678},
  author = {Mishra, Shachi and Awasthi, Pallavi and Singh, Jagriti and Gupta, Rahul Kumar and Singh, Vikram and Kant, Ruchir and Jeet, Ram and Goswami, Debabrata and Goel, Atul}
}