Nanophysics research group from 2011: (from left) Matt McCune, Dr. John Shaw, Dale Hopper, Andy Schmitz, Himadri Chakraborty
Dr. Himadri Chakraborty Northwest Missouri State University Contact Coordinates |
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07/12 – Present |
Associate Professor, Department of Natural Sciences, Northwest Missouri State University, Maryville, Missouri. |
08/06 – 06/12 |
Assistant Professor, Department of Natural Sciences, Northwest Missouri State University, Maryville, Missouri. |
02/05 – 07/06 |
Research Associate and Instructor, Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana; Attosecond Laser Pulse Generation. |
09/99 – 10/01 |
Guest Scientist, Max-Planck-Institute for the Physics of Complex System, Dresden, Germany; Photoionization of Atomic Clusters. |
08/95 – 08/99 |
Senior Scientific Officer in NSF-supported Indo-US Project, Indian Institute of Technology-Madras, Chennai, India; Photoionization of Atoms/Ions. |
Theoretical Atomic Molecular &
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DOCTORAL |
Energetic ion-atom charge transfer; Electron-impact excitations of atoms and ions |
POST-DOCTORAL |
Photoabsorption/Photoionization of atoms and atomic ions |
CURRENT |
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The pursuit of attosecond (10-18 sec) optical pulses continues unabatedly with the basic aim of chasing electrons inside an atom, just as the high-speed photography can capture an image of a bullet speeding through the air. Propagation of ultrashort IR laser pulses through a noble gas leads to the formation of single optical cycle pulses through a non-linear process called filamentation. Interestingly, the intensity of the final pulse is automatically clamped to the field ionization threshold. Utilizing this advantage we have let a filamented pulse move through a noble gas medium to create single pulses of attosecond duration via the higher order harmonic generation. Effects of carrier-envelope-phase on the final pulse formation mechanism are being investigated.
Resonant charge transfer is an important process among several processes occurring during the interaction of an ionic or a neutral species with a metal surface. Owing to the sensitivity of the process to the electronic structure of the participating candidates, it serves as a valuable probe to understand many salient structural features, namely, the effect of electronic band gap on the transfer dynamics, influence of surface symmetry and surface morphology, initial precursors to catalytic reactions on the surface etc. Significant thrust is being geared to understand the morphology of nanostructured surfaces by using anion beam as a probe with a long term goal of creating "designer's nano-surface" to catalize or de-catalize surface reactions as desired. We investigate this process by using the Cranck-Nicholson wave-packet propagation technique.
Finite systems, including atomic clusters, fullerenes, carbon nanotubes, and quantum dots are interesting objects as they exhibit properties that hover between realms of the single atom and the bulk. Contrary to the point-like atomic nucleus, a positive ion-core with a certain spatial extension provides the primary binding for valence electrons in such a system. As a result, these electrons delocalize over the ion-core and, consequently, the effective electronic potential acquires, in comparison to the atomic potential, a radically different shape: a flat interior and a sharp edge. The influence of this delocalization on both the single-electron and the collective phenomena is the focus of this topic. Calculations are performed in the time-dependent density functional theory to include electronic collectivity.
Interaction of a single photon with an atom is an excellent ``laboratory'' to understand the effects of many electron correlation. Possibility of precision measurements, owing to advance generation synchrotron light sources worldwide, motivates extensive theoretical work for detail understanding of the photo-processes. Also, photoabsorption studies, particularly involving ions, have crucial importance in numerous astrophysical applications. We employ the relativistic-random phase approximation (RRPA) to calculate the non-resonant photospectra. The autoionizing resonances are calculated by using the relativistic-multichannel quantum defect theory with RRPA combined as an adjunct.
Following the impact of positrons with matter the formation of exotic electron-positron bound-pair, the positronium (Ps), is a vital process in nature. Other than probing structure and reaction mechanism of matters, the Ps formation is a unique pathway to the electron-positron annihilation. Production of BEC of Ps, the importance of Ps in diagnosing porous materials and in probing bound-state QED effects, and its role as the precursor of the production of dipositronium molecules and antihydrogen atoms required to study the effect of gravitational force on antimatter are known. However, little attempt of Ps formation by implanting positrons in nanoparticles, particularly in gas phase, has so far been made. Our research aims at calculating and studying Ps formation cross sections from various gas-phase fullerene systems.