P.hd in Atomic, Molecular and Optical SciencesTata Institute of Fundamental Research
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P.hd in Atomic, Molecular and Optical Sciences
Most of the matter in the universe exists only in the gaseous state, and often in an ionized form. Laboratory studies with many ionized species are being pursued in the Institute to understand the processes which occur in astrophysical and plasma environments.
Lasers and heavy ion beams from an accelerator are being increasingly used in this connection. At the heart of the atom sits the nucleus. The study of nuclear structure and nuclear reactions was earlier carried out with light particle beams. A heavy-ion accelerator known as the ``Pelletron'', installed here a decade ago, has extended the studies in nuclear physics. Heavy ion beams from this accelerator, colliding with nuclei in the target, result in fusion reactions in which exotic nuclei are created. This provides the setting to investigate nuclear matter at high excitation energies and angular momenta. A superconducting linear accelerator is being developed to boost the energies of particles available from the Pelletron.
Research in atomic, molecular and optical sciences has been given a major thrust in the last few years. The interaction of high energy (MeV), highly charged ion beams are used as a probe to investigate the mechanisms of atomic collisions under weak and strong perturbations in collisions with molecules, clusters and solids: collective plasma excitations, nano-scale electron-interference, two-center post collision effect and higher order processes. Investigations using newly installed highly charged ions from ECR source can be used to probe interdisciplinary fields at low energies (keV). In addition, collision techniques that have been pursued for a long time are now being aided by lasers. The latter are used to prepare the collision targets in specific energy states to study state-selective collisions. Ultrashort (femtosecond) lasers producing very high peak powers are being used to explosively ionize matter and study its behaviour at these extreme, "implosive" excitation conditions. Nonlinear optical properties of emerging and novel materials are being studied to understand how material structure influences its optical response. The general aim of this entire work is to understand structural changes in atoms and molecules in a dynamic fashion under gentle as well as extreme external influences.
On a different note, several mesoscopic phenomena that have been the center of a physicist's curiosity are now attacked using optical waves. For example, the transition of a conductor to an insulator via Anderson localization is studied using light in a disordered medium. Nanostructured materials are used to create optical media with configurational disorder or order. The latter case leads to photonic crystals, which are believed to be templates for all-optical communication devices.
Atomic, Molecular and Optical Sciences:
* Ion-atom and ion-molecule collisions
* Interaction of electrons, ions and neutrals with laser excited molecules
* Interaction of matter in intense laser fields
* Non-linear optics
* Quantum Computing and Optical Communications
* Coherent control
* Physics of clusters
* Accelerator based atomic physics.