Interaction of Superintense, femto-second Laser Fields with Atoms, and Molecules-involving Multiphoton Processes. Collisions in Intense Short Laser Pulses. Atomic structure calculations for multi-electron atoms and ions using Configuration Interaction Technique. Electron impact Excitation Collision Strengths and Rate Coefficients having application in Astrophysics, Plasma Physics and Nuclear Fusion Reactors. Photoionization of complex ions and atoms. Study of Chemical Reactions with femto-second Laser Pulses Study of Bose-Einstein Condensate BEC in Laser Nanotechnology : Study of Non-linear Phenomenon in Nano-structures.