Connecting ultrafast molecular dynamics with real-time heat transfer and fluid mechanics: thermal diffusion, heat conduction, convection, and turbulence contributions to femtosecond time-resolved signals Alexandre Honorato, Luís C. Malacarne, Mauro L. Baesso, Matthew Pelton, Debabrata Goswami, René A. Nome Journal of Molecular Liquids, 2026 This work reports an experimental methodology to study the connection between ultrafast optical Kerr effect spectroscopy and heat transfer and fluid mechanics from femtoseconds to real time. The methodology was applied to hexane and o-dichlorobenzene, two molecular liquids with contrasting thermal diffusion behavior. We show that the ultrafast spectroscopic signals are markedly different under equilibrium (off-resonant) and nonequilibrium (resonant) conditions. By varying the intensity of the resonant pump pulses, we modulate the photothermal effect and show how transient and cumulative heating effects are manifested in the ultrafast signals. We vary the rotation rate of a magnetic stirrer to show how turbulent flow influences the signatures of heating in single-shot ultrafast measurements. We show how the time delay between pump and probe pulses can be used to characterize real-time conductive and convective modes of heat transfer as well as microscopic heat dissipation rates on the femtosecond timescale. The methodology is generally applicable to other molecular liquids and also to transparent liquids containing absorbing chromophores, which have the advantage of allowing control of the amount of heat generated after light absorption across different fluids. • Ultrafast spectroscopy measurements of liquids coupled to heat transfer and fluid mechanics. • Systems studied at equilibrium and in non-equilibrium steady-state thermal gradients. • Ultrafast measurements under heat conduction, convection, and turbulence.
Systematic Study of Third-Order Optical Nonlinearities in CS2-Based Liquid Ternary Mixtures: Thermal Lens Effects and Weak Two-Photon Absorption in Toluene Rahul Kumar Gupta, Surya Kant, Sonaly Goswami, Debabrata Goswami Chemistryselect, 2026 We present a detailed investigation of third‐order nonlinear optical properties in ternary liquid mixtures of carbon disulfide (CS 2 ), toluene, and acetone using a high‐repetition‐rate (76 MHz) femtosecond laser at 780 nm. As expected, thermal self‐defocusing and high two‐photon absorption (TPA) in CS 2 are revealed by open‐ and closed‐aperture Z‐scan measurements. Surprisingly, under these excitation settings, toluene exhibits mild, but clearly detectable TPA for the first time, challenging the long‐held belief in its near‐infrared transparency. All ternary combinations exhibit negative nonlinear refractive indices, primarily due to thermal lensing induced by cumulative heating at high repetition rates. Ideal mixing behavior and additive nonlinear contributions are demonstrated by the linear relationship between solvent composition and the TPA coefficient (β) and nonlinear refractive index (n 2 ). These findings provide new insight into the thermal and absorptive nonlinearities of organic liquids and offer a strategy for designing tunable liquid‐phase NLO media.
Convective Onset in Thermal Lensing: Systematic Pulse-Number-Dependent Experiments and Theoretical Insights into the Femtosecond Regime Aman Sharma, Debabrata Goswami Journal of Physical Chemistry B, 2026 This study investigates thermal lensing induced by femtosecond-laser pulses, a key technique for examining the thermo-optical response of materials under high-repetition-rate irradiation. Using both experimental and theoretical approaches, this work examines how thermal lensing develops and evolves over time with a focus on the effects of pulse count, pump-on duration, and pump-off duration. The study examines how conduction and convection mechanisms compete during heat dissipation, with conduction dominating at a lower number of pulses. The theoretical approach emphasizes heat generation from single-pulse interactions, which is a central aspect of this research. Importantly, the study also shows the potential thermal lens (TL) amplitude from a single femtosecond pulse, providing insights into the early stages of heat buildup. These results enhance our understanding of heat transfer in ultrafast laser-matter interactions, providing more detailed insight into how thermal lenses form and relax.
On Quantifying the Degree of Coherence in Qubits Debabrata Goswami Frontiers in Optics Fio 2025 in Proceedings Frontiers in Optics Laser Science 2025 Fio Ls Part of Frontiers in Optics Laser Science 2025, 2025
Sensitivity Unveiled: Exploring Molecular Convection through Thermal Lens Spectroscopy Frontiers in Optics Fio 2024 in Proceedings Frontiers in Optics Laser Science 2024 Fio Ls Part of Frontiers in Optics Laser Science 2024, 2024
Sensitivity Unveiled: Exploring Molecular Convection through Thermal Lens Spectroscopy Laser Science Ls 2024 in Proceedings Frontiers in Optics Laser Science 2024 Fio Ls Part of Frontiers in Optics Laser Science 2024, 2024
Theoretical Investigation on Differential Trapping by Femtosecond Optical Tweezers Laser Science Ls 2024 in Proceedings Frontiers in Optics Laser Science 2024 Fio Ls Part of Frontiers in Optics Laser Science 2024, 2024
Theoretical Investigation on Differential Trapping by Femtosecond Optical Tweezers Frontiers in Optics Fio 2024 in Proceedings Frontiers in Optics Laser Science 2024 Fio Ls Part of Frontiers in Optics Laser Science 2024, 2024
Future challenges: General discussion E. D. Jemmis, Sankarampadi Aravamudhan, Elangannan Arunan, Abhishek Shahi, Neil Hunt, Christoph Schnedermann, John R. Helliwell, Mike Ashfold, Himangshu Prabal Goswami, Artur Nenov, Volker Deckert, Priyadarshi Roy Chowdhury, Kenneth Ghiggino, R. J. Dwayne Miller, Debabrata Goswami, Wolfgang Junge, Judith Howard, Keisuke Tominaga, Tim Brandt van Driel, Martin Zanni, Siva Umapathy, Martin Meedom Nielsen, R. Pal, Shaul Mukamel Faraday Discussions, 2015
Local and Global Dynamics: General discussion Martin Zanni, E. D. Jemmis, Sankarampadi Aravamudhan, Elangannan Arunan, Neil Hunt, Sanghamitra Mukhopadhyay, Helena J. Shepherd, Srihari Keshavamurthy, Arend G. Dijkstra, Mike Ashfold, Himangshu Prabal Goswami, Artur Nenov, Himani Medhi, Kenneth Ghiggino, Kiran Moirangthem, R. J. Dwayne Miller, Debabrata Goswami, Siva Umapathy, John R. Helliwell, Jonathan D. Hirst, Stephen Meech, Shaul Mukamel, Biman Bagchi, Marylise Buron-Le Cointe Faraday Discussions, 2015
Time and Space resolved Methods: General discussion Martin Zanni, Jemmis E D, Sankarampadi Aravamudhan, Anuradha Pallipurath, Elangannan Arunan, Christoph Schnedermann, Ashok Kumar Mishra, Mark Warren, Jonathan D. Hirst, Franklin John, R. Pal, John R. Helliwell, Kiran Moirangthem, Shamik Chakraborty, Arend G. Dijkstra, Priyadarshi Roy Chowdhury, Kenneth Ghiggino, R J Dwayne Miller, Stephen Meech, Himani Medhi, Mahesh Hariharan, Freek Ariese, Alison Edwards, Ajith R. Mallia, Siva Umapathy, Martin Meedom Nielsen, Neil Hunt, Zhen-Yu Tian, Jonathan Skelton, Gopinathan Sankar, Debabrata Goswami Faraday Discussions, 2015
Dynamics of chemical bond: General discussion Kunal Dhoke, Martin Zanni, Upendra Harbola, Ravi Kumar Venkatraman, Elangannan Arunan, King-Chuen Lin, Artur Nenov, Jonathan Skelton, R J Dwayne Miller, Jonathan D. Hirst, Vincenzo Aquilanti, John R. Helliwell, Srihari Keshavamurthy, Sai Ramesh, Mike Ashfold, Anuradha Pallipurath, Priyadarshi Roy Chowdhury, Sanghamitra Mukhopadhyay, Jemmis E D, Himani Medhi, Debabrata Goswami, Prasenjit Halder, Wolfgang Junge, Mahesh Hariharan, Santosh Kumar Singh, Siva Umapathy, Adithya Lakshmannam, Martin Meedom Nielsen, Sankarampadi Aravamudhan, Volker Deckert, Kenneth Ghiggino, Keisuke Tominaga, Alison Edwards Faraday Discussions, 2015
Highly nonlinear femtosecond processes in liquid phase: Water cluster Raman spectra and microheterogeneity induced coherent oscillations Proceedings 12th International Conference on Fiber Optics and Photonics Photonics 2014, 2014
Insignificance of relative time delay between photons for a ultrafast two-photon process 2012 International Conference on Fiber Optics and Photonics Photonics 2012, 2012
Study of self defocusing in liquids using single beam Z-scan with high repetition rate laser pulses 2012 International Conference on Fiber Optics and Photonics Photonics 2012, 2012
Study of self defocusing in liquids using single beam Z-scan with High repetition rate laser pulses Optics Infobase Conference Papers, 2012
Thermal-lens spectroscopy in binary liquids mixtures: Effect of isotope substitution Optics Infobase Conference Papers, 2011
Polarization modulated Ultrafast pulse-pair control in two-photon fluorescence microscopy Optics Infobase Conference Papers, 2011
Towards using molecular states as qubits Debabrata Goswami, Tapas Goswami, S. K. Karthick Kumar, Dipak K. Das, Dipankar Home, Guruprasad Kar, Archan S. Majumda Aip Conference Proceedings, 2011
Two-photon fluorescence diagnostics of femtosecond laser tweezers Current Science, 2011
Single experimental setup for high sensitive absorption coefficient and optical nonlinearities measurements Lasers and Electro Optics Research at the Cutting Edge, 2007
Altering excitation dynamics in optically dense media using shaped ultrafast laser pulses IQEC International Quantum Electronics Conference Proceedings, 1999
Altering excltatlon dynamics in optically dense media using shaped ultrafast laser pulses Optics Infobase Conference Papers, 1999
Optical wavelength domain code-division multiplexing using an AOM-based ultrafast optical pulse shaping approach Proceedings of SPIE the International Society for Optical Engineering, 1998
Linear and Nonlinear Spectroscopic Insights Into the Synergistic Solvation of Rhodamine-6G in Methanol-Dichloromethane Binary Solvent Mixture RK Gupta, S Kant, D Goswami Journal of Fluorescence, 1-11 , 2026 2026
Characterizing colloidal clusters with femtosecond optical tweezers A Singh, KK Singh, D Mondal, D Kumar, D Goswami Journal of the Optical Society of America A 43 (8), D44-D49 , 2026 2026
Unveiling the thermal transport pathways in chloroalkane binary liquid mixtures: A combined femtosecond thermal Lens spectroscopy and molecular dynamics study S Paul, S Chakraborty, D Goswami Journal of Molecular Liquids, 129610 , 2026 2026
Exploring solvent-acid thermal dynamics through thermal Lens spectroscopy in diverse media SK Gupta, A Sharma, D Goswami Journal of Molecular Liquids, 129549 , 2026 2026
Systematic Study of Third‐Order Optical Nonlinearities in CS 2 ‐Based Liquid Ternary Mixtures: Thermal Lens Effects and Weak Two‐Photon Absorption in Toluene RK Gupta, S Kant, S Goswami, D Goswami ChemistrySelect 11 (16), e00059 , 2026 2026
Connecting ultrafast molecular dynamics with real-time heat transfer and fluid mechanics: thermal diffusion, heat conduction, convection, and turbulence contributions to … A Honorato, LC Malacarne, ML Baesso, M Pelton, D Goswami, RA Nome Journal of Molecular Liquids, 129516 , 2026 2026
Coherent Control of Laser-Induced Periodic Surface Structures on Molybdenum via Ultrafast Laser Writing S Paul, MA Taher, V Pathak, D Goswami Journal of Alloys and Compounds Communications, 100172 , 2026 2026
Convective Onset in Thermal Lensing: Systematic Pulse-Number-Dependent Experiments and Theoretical Insights into the Femtosecond Regime A Sharma, D Goswami The Journal of Physical Chemistry B , 2026 2026 Citations: 1
Facile One-pot Synthesis of Triply-Fused, Fluorescent Chlorin-porphyrin Heterodimers with Near-IR Absorption: Impact of π-Conjugation on Optical Properties SJ Shah, A Sharma, B Khamrui, A Roychowdhury, D Goswami, SP Rath Inorganic Chemistry Frontiers , 2026 2026
Correction: Differential optical trapping of nanoparticles with a single femtosecond laser beam D Kumar, A Singh, KK Singh, D Goswami Optical and Quantum Electronics 57 (12), 635 , 2025 2025
Photothermal Transport Perturbation in Methanol-Water Binary System Using Non-Absorbing Fluorescein Dye S Kotwal, A Sharma, D Goswami Frontiers in Optics, JV8A. 4 , 2025 2025
Optical Trapping of Microparticles in Various Dispersion Media under CW and Pulsed Modes D Kumar, A Singh, KK Singh, D Goswami Laser Science, JD1A. 35 , 2025 2025
On Quantifying the Degree of Coherence in Qubits D Goswami Laser Science, JV5A. 3 , 2025 2025
Revealing synergistic photo-thermal lens effects in binary DMF mixtures A Sharma, S Kant, S Kotwal, D Goswami Journal of Molecular Liquids, 128734 , 2025 2025 Citations: 3
Connecting ultrafast molecular dynamics with real-time heat transfer and fluid mechanics: application to hexane, o-dichlorobenzene, and their equimolar mixture A Honorato, M Baesso, L Malacarne, D Goswami, R NOME ChemRxiv 2025 (1002) , 2025 2025
Coherent Control of Laser-Induced Periodic Surface Structures via Ultrafast Nanoengineering D Goswami, S Paul, M Abu Taher, V Pathak Available at SSRN 5604825 , 2025 2025
Femtosecond-laser-induced optical confinement with ping-pong motion KK Singh, A Singh, D Kumar, D Goswami The Journal of Chemical Physics 163 (10) , 2025 2025 Citations: 1
Differential optical trapping of nanoparticles with a single femtosecond laser beam D Kumar, A Singh, KK Singh, D Goswami Optical and Quantum Electronics 57 (9), 520 , 2025 2025
Solvent effect on multiple emission and femtosecond dynamics of higher-lying excited states: Evidence of microheterogeneity induced coherent oscillations D Goswami ACS Fall 2025 , 2025 2025
Compositional Analysis of Fragrance Accords Using Femtosecond Thermal Lens Spectroscopy R Goswami, AK Rawat, S Goswami, D Goswami Chemistry–An Asian Journal 20 (17), e00521 , 2025 2025 Citations: 2
MOST CITED SCHOLAR PUBLICATIONS
Femtosecond laser pulse shaping by use of microsecond radio-frequency pulses CW Hillegas, JX Tull, D Goswami, D Strickland, WS Warren Optics Letters 19 (10), 737-739 , 1994 1994 Citations: 449
Optical pulse shaping approaches to coherent control D Goswami Physics Reports 374 (6), 385-481 , 2003 2003 Citations: 397
Adiabatic population transfer with frequency‐swept laser pulses JS Melinger, SR Gandhi, A Hariharan, D Goswami, WS Warren The Journal of chemical physics 101 (8), 6439-6454 , 1994 1994 Citations: 266
Ultrafast pulse shaping: amplification and characterization MR Fetterman, D Goswami, D Keusters, W Yang, JK Rhee, WS Warren Optics Express 3 (10), 366-375 , 1998 1998 Citations: 236
Core-modified expanded porphyrins with large third-order nonlinear optical response H Rath, J Sankar, V PrabhuRaja, TK Chandrashekar, A Nag, D Goswami Journal of the American Chemical Society 127 (33), 11608-11609 , 2005 2005 Citations: 217
Zinc (II)-and copper (I)-mediated large two-photon absorption cross sections in a bis-cinnamaldiminato Schiff base S Das, A Nag, D Goswami, PK Bharadwaj Journal of the American Chemical Society 128 (2), 402-403 , 2006 2006 Citations: 154
Nonlinear absorption in tetrathia[22]porphyrin(2.1.2.1)s: visualizing strong reverse saturable absorption at non-resonant excitation K Singh, S Arora, K Makhal, P Kaur, D Goswami RSC Advances 6, 22659-22663 , 2016 2016 Citations: 137
Solvent effect on two-photon absorption and fluorescence of rhodamine dyes A Nag, D Goswami Journal of Photochemistry and Photobiology A: Chemistry 206 (2-3), 188-197 , 2009 2009 Citations: 127
Stable optical trapping of latex nanoparticles with ultrashort pulsed illumination AK De, D Roy, A Dutta, D Goswami Applied Optics 48 (31), G33-G37 , 2009 2009 Citations: 93
Laser-enhanced NMR spectroscopy WS Warren, S Mayr, D Goswami, AP West Jr Science 255 (5052), 1683-1685 , 1992 1992 Citations: 85
22π smaragdyrin molecular conjugates with aromatic phenylacetylenes and ferrocenes: syntheses, electrochemical, and photonic properties R Misra, R Kumar, TK Chandrashekar, CH Suresh, A Nag, D Goswami Journal of the American Chemical Society 128 (50), 16083-16091 , 2006 2006 Citations: 83
Aromatic core modified decaphyrins with the largest two-photon absorption cross-sections: syntheses and characterization H Rath, V Prabhuraja, TK Chandrashekar, A Nag, D Goswami, BS Joshi Organic Letters 8 (11), 2325-2328 , 2006 2006 Citations: 66
Coherent control of multiphoton transitions with femtosecond pulse shaping SA Hosseini, D Goswami Physical Review A 64 (3), 033410 , 2001 2001 Citations: 63
Suppression of supercontinuum generation with circularly polarized light AS Sandhu, S Banerjee, D Goswami Optics communications 181 (1-3), 101-107 , 2000 2000 Citations: 57
Importance of molecular heat convection in time resolved thermal lens study of highly absorbing samples P Kumar, A Khan, D Goswami Chemical Physics 441, 5-10 , 2014 2014 Citations: 52
Two-photon cross-section measurements using an optical chopper: z -scan and two-photon fluorescence schemes A Nag, AK De, D Goswami Journal of Physics B: Atomic, Molecular and Optical Physics 42 (6), 065103 , 2009 2009 Citations: 50
Coumarin derived chromophores in the donor–acceptor–donor format that gives fluorescence enhancement and large two-photon activity in presence of specific metal ions D Ray, A Nag, A Jana, D Goswami, PK Bharadwaj Inorganica Chimica Acta 363 (12), 2824-2832 , 2010 2010 Citations: 49
Rapid ultrafine-tunable optical delay line at the 1.55- µ m wavelength W Yang, D Keusters, D Goswami, WS Warren Optics letters 23 (23), 1843-1845 , 1998 1998 Citations: 49
Probing intermolecular interaction through thermal-lens spectroscopy I Bhattacharyya, P Kumar, D Goswami The Journal of Physical Chemistry B 115 (2), 262-268 , 2011 2011 Citations: 48
Modified (22π) smaragdyrins with large two-photon absorption cross section: a structure function correlation R Misra, R Kumar, TK Chandrashekar, A Nag, D Goswami Organic Letters 8 (4), 629-631 , 2006 2006 Citations: 48
