| Description |
Abstract:
Ion momentum imaging has developed into an area of major activity in atomic collision physics in the last 20 years to obtain intricate dynamics of the collision process as well structure of molecules. Historically two different techniques emerged in parallel – Recoil Ion Momentum spectroscopy with its more refined version Cold Target Recoil Ion Momentum Spectrometry (COLTRIM) and Velocity Map Imaging. The first one was developed by the ion-atom collision physicists and the second one by physical chemists for studying photodissociation of molecules. While both these techniques have been used in variety of collision phenomena looking at either electrons or positive ions, there remained a big void on implementing these for negative ions, in particular for dissociative electron attachment (DEA) in which a very low energy electron fragments a molecule forming a negative ion. This process full of rich dynamics and provides the unique opportunity of studying the transient states of molecular negative ions, has been in limelight due to its importance in plethora of applications starting from radiation biology to astrochemistry. In this colloquium, I will present developments on the ion momentum imaging techniques and the unique role of TIFR in developing negative ion momentum imaging for DEA studies.
About the Speaker:
E. Krishnakumar did his Ph. D. from PRL Ahmedabad on low energy photoelectron spectrometry of gas phase molecules. He has been at TIFR since 1988 after a stint with ISRO and postdoctoral work at the Jet Propulsion Lab, CALTECH. Has worked on diverse aspects of Atomic Collision Physics including photoionization, electron scattering, ion – atom/molecule collisions, photodetachment of negative ions, VUV and beam foil spectrometry, ultrafast dynamics in photoionization using atto-second high harmonic pulses, electron ionization, dissociative electron attachment and electron collisions in condensed phase. He is well known in the atomic collision community across the world for the development of new techniques for measurement of absolute cross sections for electron ionization and attachment, chemical control using electrons and the development of a new ion momentum imaging technique for the difficult art of low energy electron-molecule collisions, which has provided several new insights into the physics of electron-molecule interactions.
|