A5060307956- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- Spectroscopy and Quantum Chemical Studies
- Atomic and Subatomic Physics Research
- Ion-surface interactions and analysis
- Quantum, superfluid, helium dynamics
- Atmospheric Ozone and Climate
- Photoreceptor and optogenetics research
- Cold Atom Physics and Bose-Einstein Condensates
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Photochromic and Fluorescence Chemistry
- Advanced Electron Microscopy Techniques and Applications
- Photocathodes and Microchannel Plates
- Laser-Plasma Interactions and Diagnostics
- Molecular Spectroscopy and Structure
- Analytical Chemistry and Sensors
- Laser-induced spectroscopy and plasma
- Plasma Diagnostics and Applications
- Laser-Matter Interactions and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy and Laser Applications
- Electron and X-Ray Spectroscopy Techniques
- Dust and Plasma Wave Phenomena
Indian Institute of Science Education and Research Kolkata
2013-2024
Indian Institute of Science Education and Research, Tirupati
2020-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2010-2013
Centre National de la Recherche Scientifique
2010-2013
Seoul National University
2013
Indian Institute of Science Bangalore
2013
Laboratoire Francis Perrin
2010-2011
Freie Universität Berlin
2001-2009
Tata Institute of Fundamental Research
2001-2009
Max Planck Society
2007
We studied the photoionization of 2-pyridone and its tautomer, 2-hydroxypyridine by means VUV synchrotron radiation coupled to a velocity map imaging electron/ion coincidence spectrometer. The efficiency (PIE) spectrum is composed steps. state energies [2-pyridone]+ cation in ground à excited electronic states, as well [2-hydroxypyridine]+ state, are determined. slow photoelectron spectra (SPES) dominated 000 transitions corresponding states together with several weaker bands population pure...
Functional group dependence is observed in the dissociative electron attachment (DEA) to various organic molecules which DEA features seen precursor of groups are retained bigger molecules. This functional lead site-selective fragmentation these at hydrogen sites. The results explained terms formation core-excited Feshbach resonances. point a simple way controlling chemical reactions as well interpreting data from biological
A velocity slice imaging method is developed for measuring the angular distribution of fragment negative ions arising from dissociative electron attachment (DEA) to molecules. low energy pulsed gun, a field ion extraction, and two-dimensional position sensitive detector consisting microchannel plates wedge-and-strip anode are used this purpose. Detection storage each separately its flight time allows analysis data offline any given slice, without resorting pulsing bias. The performance...
Two-photon photoemission spectroscopy is employed to elucidate the electronic structure and excitation mechanism in photoinduced isomerization of molecular switch tetra-tert-butyl-azobenzene (TBA) adsorbed on Au(111). Our results demonstrate that optical switching at a metal surface completely different compared corresponding process for free molecule. In contrast direct (intramolecular) operative liquid phase, conformational change surface-bound TBA driven by substrate-mediated charge...
Dissociative electron attachment (DEA) cross sections for simple organic molecules, namely, acetic acid, propanoic methanol, ethanol, and n-propyl amine are measured in a crossed beam experiment. We find that the H− ion formation is dominant channel of DEA these molecules takes place at relatively higher energies (>4eV) through core excited resonances. Comparison from with those NH3, H2O, CH4 shows presence functional group dependence process. analyze this new phenomenon context...
Complete dissociation dynamics in electron attachment to carbon monoxide (CO) have been studied using the newly developed velocity slice imaging (VSI) technique. Both kinetic energy and angular distributions of O(-) ions formed by dissociative (DEA) CO molecules measured for 9, 9.5, 10, 10.5, 11, 11.5 eV incident energies around resonance. Detailed observations conclusively show that two separate DEA reactions lead formation ground (2)P state along with neutral C atoms (3)P first excited...
How much time does it take for a wavepacket to roam on multidimensional potential energy surface? This combined theoretical and pump-probe femtosecond experiment 2-hydroxypyridine proposes an answer. Bypassing the well-established transition state conical intersection relaxation pathways, this molecular system undergoes into S1 excited state: central ring is destabilized by electronic excitation, within ~100 fs after absorption of pump photon, then H-atom bound oxygen roaming behavior when...
Dissociative electron attachment (DEA) to gas phase ${\mathrm{CO}}_{2}$ has been probed using a velocity slice imaging technique. DEA produces only an ${\mathrm{O}}^{\ensuremath{-}}$ ionic fragment and shows two major resonances located at 4.4 8.2 eV, respectively. The kinetic energy angular distribution of the ions are measured around second resonance with higher efficiency sensitivity that provide details dynamics. distributions in good agreement previous reports. However, distinct show...
An experimental and theoretical investigation of the dissociative electron attachment process in nitric oxide is presented. Measurements using recently developed ion momentum imaging conclusively show presence two resonance features O(-) channel. These are found to dissociate give N atoms (2)D (2)P excited states respectively, thus settling controversies regarding possible dissociation limits this process. Though angular distribution shows resonances contributing these dissociations Π...
The structure and dynamics of the negative ion resonances leading to dissociative electron attachment in N2O are studied using velocity slice imaging technique. Distinct momentum distributions observed O− channel for dominant below 4 eV which considerably different than those reported so far. Also relatively weak but distinct at 8.1 13.2 their first time. For each these two channels dissociation with differing angular distributions.
Fragmentation dynamics of ion-pair states carbon monoxide in electron collisions through direct and indirect excitation.
A complete data acquisition system has been developed that can work with any personal computer irrespective of the operating installed on it. The software be used in low and intermediate electron-energy collision studies ground-state molecules gas phase using a combination RS-232, GPIB, USB-interfaced devices. Various tabletop instruments nuclear instrumentation module (NIM) -based electronics have interfaced communicated software, which is based LabVIEW. This tested dissociative electron...
Evidence for the presence of 4Σu− resonance in dissociative electron attachment to O2 is obtained first time from angular distribution measurement O− ions entire 2π angles using a novel experimental technique employing velocity map imaging. This observation, while settling question this state observed inelastic vibrational excitation O2, calls fresh calculations on lifetime resonance. It may also impact interpretations negative ion formation clusters and condensed state.
A new time of flight mass spectrometer (TOFMS) has been developed to study the absolute dissociative electron attachment (DEA) cross section using a relative flow technique wide variety molecules in gas phase, ranging from simple diatomic complex biomolecules. Unlike Wiley-McLaren type TOFMS, here total ion collection condition achieved without compromising resolution by introducing field free drift region after lensing arrangement. The interaction is provided for low energy molecule...
We report a complete kinematic study of ${\mathrm{O}}^{\ensuremath{-}}$-ion formation due to dissociative electron attachment ${\mathrm{SO}}_{2}$ using the velocity slice imaging technique in incident energy range over resonances. Two resonances are observed at 5.2 and 7.5 eV, respectively. From kinetic distribution, two have same threshold energy, pointing fact that processes, giving rise resonant peaks, dissociation limit. angular distribution results we identified involvement an ${A}_{1}$...