A5018858395- Quantum, superfluid, helium dynamics
- Advanced Chemical Physics Studies
- Atomic and Subatomic Physics Research
- Laser-Matter Interactions and Applications
- Laser Material Processing Techniques
- Photonic and Optical Devices
- Advanced Antenna and Metasurface Technologies
- Photonic Crystals and Applications
- Atomic and Molecular Physics
- Spectroscopy and Quantum Chemical Studies
- 2D Materials and Applications
- Advanced Fiber Laser Technologies
- Laser-Plasma Interactions and Diagnostics
- Nonlinear Optical Materials Studies
- Ocular and Laser Science Research
- Adhesion, Friction, and Surface Interactions
- Tribology and Lubrication Engineering
- Laser-induced spectroscopy and plasma
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum Dots Synthesis And Properties
- High-pressure geophysics and materials
- Plasmonic and Surface Plasmon Research
- Mass Spectrometry Techniques and Applications
- Metamaterials and Metasurfaces Applications
- Laser Design and Applications
Indian Institute of Technology Madras
2016-2025
Indian Institute of Technology Tirupati
2023
Vellore Institute of Technology University
2023
Geotechnical and Structures Laboratory
2021
University of Illinois Urbana-Champaign
2021
Aarhus University
2019
University of Connecticut
2019
Elettra-Sincrotrone Trieste S.C.p.A.
2019
T. D. Medical College
2018
Ashok Leyland (India)
2010
Irradiation of condensed matter with ionizing radiation generally causes direct photoionization as well secondary processes that often dominate the ionization dynamics. Here, large helium (He) nanodroplets radius≳40nm doped lithium (Li) atoms are irradiated extreme ultraviolet (XUV) photons energyhν⩾44.4 eV and indirect Li dopants is observed in addition to He droplets. Specifically, ions efficiently produced by an interatomic Coulombic decay (ICD) process involving metastable He∗atoms...
Herein, MoS2 quantum dots (QDs) with controlled optical, structural, and electronic properties are synthesized using the femtosecond pulsed laser ablation in liquid (fs-PLAL) technique by varying pulse width, power, time to harness potential for next-generation optoelectronics technology. Furthermore, this work elucidates key aspects of mechanisms underlying near-UV blue emissions accompanying large Stokes shift, consequent change sample color exposure parameters pertaining QDs. Through...
Abstract Irradiation of condensed matter with ionizing radiation generally causes direct photoionization as well secondary processes that often dominate the ionization dynamics. Here, large helium (He) nanodroplets radius ≳ 40 nm doped lithium (Li) atoms are irradiated extreme ultraviolet (XUV) photons energy hν ≥ 44.4 eV and indirect Li dopants is observed in addition to He droplets. Specifically, ions efficiently produced by an interatomic Coulombic decay (ICD) process involving metastable...
Abstract Roaming reactions involving a neutral fragment of molecule that transiently wanders around another before forming new bond are intriguing and peculiar pathways for molecular rearrangement. Such can occur example upon double ionization small organic molecules, have recently sparked much scientific interest. We studied the dynamics $$\hbox {H}_2$$ -roaming reaction leading to formation {H}_3^+$$ after two-photon ethanol 2-aminoethanol, using an XUV-UV pump-probe scheme. For ethanol,...
The emergence of quasiparticles in interacting matter is a fundamental aspect contemporary physics, driving the pursuit novel particles or phenomena that could shed light on mechanisms and improve photocatalytic photoelectrocatalytic efficiency MoO3. This work extensively studied structural, vibrational, optical properties lattice distortions by oxygen defects MoO3–x nanostructures. An additional Raman mode (∼1003 cm-1) appeared α-MoO3 nanobelts due to vacancies also related morphology...
Interatomic Coulombic decay (ICD) plays a crucial role in weakly bound complexes exposed to intense or high-energy radiation. So far, neutral ionic atoms molecules have been prepared singly excited electron hole states that can transfer energy neighboring centers and cause ionization radiation damage. Here we demonstrate doubly atom, despite its extremely short lifetime, by ICD; evidenced high-resolution photoelectron spectra of He nanodroplets the 2s2p+ state. We find ICD proceeds...
Photoionization spectroscopy and mass spectrometry of doped helium (He) nanodroplets rely on the ability to efficiently detect ions and/or electrons. Using a commercial quadrupole spectrometer photoelectron-photoion coincidence spectrometer, we systematically measure yields electrons created in pure He wide size range two ionization regimes-direct secondary after resonant photoexcitation droplets. For different types dopants (oxygen molecules, O2, lithium atoms, Li), infer optimal droplet...
The emission of photoelectrons from superfluid helium nanodroplets is affected by the droplet size due to elastic electron-helium scattering; in large droplets, a shadowing effect leads preferential toward incident photon beam.
Interatomic Coulombic decay (ICD) processes play a crucial role in weakly bound complexes exposed to intense or high-energy radiation. Using large helium nanodroplets, we demonstrate that ICD is efficient even when the droplets are irradiated by weak synchrotron radiation at relatively low photon energies. Below ionization threshold, resonant excitation of multiple centers efficiently induces as previously observed for pulses [A. C. LaForge , ]. More surprisingly, observe above threshold due...
Abstract We investigate the ionisation and fragmentation dynamics of free camphor molecules camphor-doped helium nanodroplets by extreme ultraviolet (EUV) soft x-ray photons using velocity map imaging combined with photoelectron-photoion coincidence (VMI-PEPICO) spectroscopy. notably find that Penning in He at <?CDATA $h\nu = 21.43$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>h</mml:mi> <mml:mi>ν</mml:mi> <mml:mo>=</mml:mo> <mml:mn>21.43</mml:mn>...
Temperature-dependent vibrational characteristics of scissors modes α-MoO 3 in terms Fano resonance and anharmonicity.
In this Letter, we report on the design, fabrication, and implementation of a novel plasmon-mode-driven low-threshold near-infrared (NIR) random laser (RL) in 850-900 nm range based plasmonic ZnS@Au core-shell scatterers. Plasmon modes NIR region are used for nanoscale scatterer engineering particles to enhance scattering, as against pristine ZnS. This scattering enhancement coupled with femtosecond (fs) pumping is shown cause three-fold lasing threshold reduction from 325 μJ/cm2 100 mode...
To determine whether the large doses of thyroxine treatment early in life adversely affect bone mass, we measured mass 20 congenital hypothyroid (CH) patients (8.4 +/- 2.2 years) who were diagnosed and treated since birth. Starting dose current 8.5 1.9 micrograms/kg/day 3.1 + 1.2 respectively. Thyroid function serum biochemical tests for calcium homeostasis normal at time study. Bone was by dual energy X-ray absorptiometry. Nine siblings served as controls. The patients' mineral density...
Doubly-excited Rydberg states of helium (He) nanodroplets have been studied using synchrotron radiation. We observed Fano resonances related to the atomic N = 2,0 series as a function droplet size. Although similar qualitatively their counterparts, resonance lines are broader and exhibit shift in energy which increases for higher excited states. Furthermore, additional not seen systems. discuss these features terms delocalized perturbed by surrounding He atoms compare singly droplets.
Helium nanodroplets (“HNDs”) are widely used for forming tailor-made clusters and molecular complexes in a cold, transparent, weakly interacting matrix. The characterization of embedded species by mass spectrometry is often complicated the fragmentation trapping ions HNDs. Here, we systematically study fragment ion spectra HND-aggregated water oxygen following their ionization charge transfer (“CTI”) Penning (“PEI”). While efficiency PEI lower than CTI about factor 10, both mean sizes...
In the present work, we report plasmon induced brightening of dark excitons (XD) in Au nanoparticle (Au-NP) coated monolayer (1L) WSe2. We observed one order enhancement photoluminescence (PL) intensity and surface enhanced Raman scattering Au-NP/1L-WSe2 at room temperature (RT). Temperature dependent PL measurements showed emission from RT down to 100 K contrast reduced which is generally for pristine 1L-WSe2. attribute this effect out-of-plane electric field by Au-NPs, results dipole...
Superfluid helium nanodroplets are often considered as transparent and chemically inert nanometer-sized cryo-matrices for high-resolution or time-resolved spectroscopy of embedded molecules clusters. On the other hand, when resonantly excited with XUV radiation, a multitude ultrafast processes initiated, such relaxation into metastable states, formation nanoscopic bubbles excimers, autoionization channels generating low-energy free electrons. Here, we discuss full spectrum observed...
The need for improved UV emitting luminescent materials underscored by applications in optical communications, sterilization and medical technologies is often addressed wide bandgap semiconducting oxides. Among these, the Mg-doped ZnO system of particular interest as it offers opportunity to tune emission engineering its via doping control. However, both doped pristine congener, ZnO, suffer from being highly prone parasitic defect level emissions, compromising their efficiency light emitters...
Abstract Low‐dimensional transition metal dichalcogenide (TMDC) materials are heralding a new era in optoelectronics and valleytronics owing to their unique properties. Photo‐induced dynamics these systems is mostly studied from the perspective of individual quasi‐particles—excitons, bi‐excitons, or, even, trions—their formation, evolution, decay. The role multi‐body exciton dynamics, associated collective behavior, condensation, inter‐excitonic interactions remain intriguing seek attention,...
Radiation damage in a biological system is studied by secondary ionization of dopant clusters helium nanodroplets following excitation or the droplet matrix.
Abstract Femtosecond laser-assisted surface texturing of compression piston rings is proposed and demonstrated. A femtosecond pulsed Ti3+:sapphire laser used to generate dimples the same size but with different area density on a moly-chrome ceramic deposited cast iron ring. The influence morphology tribology operating conditions, such as reciprocating frequency temperature lubricant, friction wear characteristics textured plateau honed liner samples investigated. decrease in coefficient...
We present single-shot electron velocity-map images of nanoplasmas generated from doped helium nanodroplets and neon clusters by intense near-infrared mid-infrared laser pulses. report a large variety signal types, most crucially depending on the cluster size. The common feature is two-component distribution for each single-cluster event: A bright inner part with nearly circular shape corresponding to energies up few eV, surrounded an extended background more energetic electrons. total...
We demonstrate for the first time, to best of our knowledge, Raman random lasing in a continuous-wave (CW) excited, completely biocompatible and biodegradable carrot medium naturally composed fibrous cellulose scattering rich carotene gain medium. The CW-laser-induced photoluminescence threshold linewidth analysis at Stokes modes show characteristic action with 130 W/cm2 narrowing mode Q factor up 1300. Polarization study output reveals that mostly retains source polarization state. A neat...