A5043868604- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Laser-Matter Interactions and Applications
- X-ray Diffraction in Crystallography
- Analytical Chemistry and Chromatography
- Crystallization and Solubility Studies
- Radical Photochemical Reactions
- Multiferroics and related materials
- Mass Spectrometry Techniques and Applications
- Molecular spectroscopy and chirality
- Ferroelectric and Piezoelectric Materials
- Electron and X-Ray Spectroscopy Techniques
- Advanced Fiber Laser Technologies
- Advanced Electron Microscopy Techniques and Applications
- Molecular Spectroscopy and Structure
- Surface Chemistry and Catalysis
- Atomic and Subatomic Physics Research
- Fluorine in Organic Chemistry
- Photochromic and Fluorescence Chemistry
- Dielectric properties of ceramics
- Inorganic Fluorides and Related Compounds
- MXene and MAX Phase Materials
- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy and Laser Applications
University of Nebraska–Lincoln
2016-2024
Techno India University
2023
Bangladesh University of Engineering and Technology
2014-2016
University of Dhaka
2014
Identifying multiple rival reaction products and transient species formed during ultrafast photochemical reactions determining their time-evolving relative populations are key steps toward understanding predicting outcomes. Yet, most contemporary studies struggle with clearly identifying quantifying competing molecular structures/species among the emerging products. Here, we show that mega-electronvolt electron diffraction in combination ab initio dynamics calculations offer a powerful route...
Conformational isomers or conformers of molecules play a decisive role in chemistry and biology. However, experimental methods to investigate chemical reaction dynamics are typically not conformer-sensitive. Here, we report on gas-phase megaelectronvolt ultrafast electron diffraction investigation {\alpha}-phellandrene undergoing an electrocyclic ring-opening reaction. We directly image the evolution specific set into product isomer predicted by Woodward-Hoffmann rules real space time. Our...
Abstract Electrocyclic reactions are characterized by the concerted formation and cleavage of both σ π bonds through a cyclic structure. This structure is known as pericyclic transition state for thermal minimum in excited photochemical reactions. However, geometry has yet to be observed experimentally. We use combination ultrafast electron diffraction wavepacket simulations image structural dynamics electrocyclic ring-opening reaction molecule α-terpinene. The motion into dominated...
We investigated the ultrafast structural dynamics of cyclobutanone following photoexcitation at $\lambda=200$ nm using gas-phase megaelectronvolt electron diffraction. Our investigation complements simulation studies same process within this special issue. It provides information about both electronic state population and through well-separable inelastic elastic scattering signatures. observe depopulation photoexcited S$_2$ with n3s Rydberg character its signature a time constant $(0.29 \pm...
The structural dynamics of photoexcited gas-phase carbon disulfide (CS2) molecules are investigated using ultrafast electron diffraction. were triggered by excitation the optically bright 1B2(1Σu+) state an ultraviolet femtosecond laser pulse centred at 200 nm. In accordance with previous studies, rapid vibrational motion facilitates a combination internal conversion and intersystem crossing to lower-lying electronic states. Photodissociation via these manifolds results in production CS...
We investigate the fragmentation and isomerization of toluene molecules induced by strong-field ionization with a femtosecond near-infrared laser pulse.
An ultrafast electron diffraction study of the structural dynamics cis , -1,3-cyclooctadiene has identified a ring stretching distortion as new reaction coordinate molecule transitions from excited state back to ground state.
Ultrafast electron diffraction (UED) from aligned molecules in the gas phase has successfully retrieved structures of both linear and symmetric top molecules. Alignment asymmetric tops been recorded with UED but no structural information was retrieved. We present here extraction two-dimensional simple transformations experimental patterns as a proof-of-principle for recovery full structure. align 4-fluorobenzotrifluoride linearly polarized laser show that we can distinguish between atomic...
Imaging laser-induced rotational dynamics is an important and active field due to its applications in capturing reactions the molecular frame imaging. Experimental measurement of orientation distribution, as a function Euler angles, has been demonstrated for special cases when detectable signal generated along symmetry axis. Here we developed general theory that maps probability density distribution atom-pair angular distributions nonlinear molecules. With theory, can be retrieved from...
We report the modification of a gas phase ultrafast electron diffraction (UED) instrument that enables experiments with both and condensed matter targets, where time-resolved experiment sub-picosecond resolution is demonstrated solid state samples. The relies on hybrid DC-RF acceleration structure to deliver femtosecond pulses target, which synchronized laser pulses. are used excite sample probe structural dynamics, respectively. new system added capabilities perform transmission UED thin It...
Abstract Gas phase electron diffraction is a powerful technique to measure the structure of molecules in gas phase, and time-resolved ultrafast has been successful capturing structural dynamics taking place on femtosecond picosecond time scales. Diffraction measurements, however, are not sensitive isotope substitution, thus cannot distinguish between isotopologues. Here we show that by impulsively aligning with short laser pulse observing anisotropy signal over multiple revivals rotational...
We imaged the conformer-specificity of an electrocyclic ring-opening reaction as predicted by Woodward-Hoffmann rules in real space and time employing a combination ultrafast electron diffraction excited state dynamics simulations.
Abstract Imaging laser-induced rotational dynamics is an important and active field due to its applications in capturing reactions the molecular frame imaging. Ultrafast electron diffraction has been a powerful tool study of wavepackets, however, studies have limited linear molecules challenges retrieving probability density from signal for nonlinear molecules. Here we show that can directly retrieve time-dependent symmetric top were impulsively aligned by femtosecond laser pulse. The...
Abstract Fill factor and conversion efficiency of single heterojunction solar cell is analytically computed based on the shallow doping at GaAs quantum well region. Poisson’s equation solved with suitable boundary condition applied hetero-interface for both dark illuminated conditions, corresponding to which open-circuit voltage short-circuit current are computed. Realistic dependence minority carrier distribution material layers diffusion widths taken into account simulation purpose. Result...
Identifying multiple rival reaction products and transient species formed during ultrafast photochemical reactions determining their time-evolving relative populations are key steps towards understanding predicting outcomes. Yet, most contemporary studies struggle with clearly identifying quantifying competing molecular structures/species amongst the emerging products. Here, we show that mega-electronvolt electron diffraction in combination ab initio dynamics calculations offer a powerful...