Annual Report 2005-2006

Science & Engineering Research Council

Physical Sciences

Condensed Matter Physics and Materials Science

New projects supported are:

• Study of organic luminescent materials for optoelectronic devices;
  
• Electronic and magnetic structure of transition metal alloys;
  
• Setting up of single Crystal X-ray Diffractometer as a National Facility in Jammu University;
  
• Synthesis and characterization of b-FeSi2 thin films for optoelectronic device applications;
  
• Investigation of deep level defects in GaN using DLTS technique;
  
• Investigation of electrical conductivity of doped silver halides;
• Development of photoactive glass-fullerene hetero-structures and studies on the viability of their use in designing photodiode and photo-voltaic cell;
• Study of electronic structure of some materials by HF-LCAO method;
• Energy dispersive experiments using gamma-rays;
• Ab initio calculation of electronic properties of novel magnetic materials;
• Dynamics of membranes and micellar solutions;
• Study of rheology, adhesion and viscous fingering in soft matter;
• Electronic transport in quantum confined semiconductor structure at low lattice temperatures;
• SHI induced nanostructure formation of oxide thin films;
• Preparation and characterization of transparent conducting cadmium stannate and zinc stannate thin films from low cost new precursors by Spray Pyrolysis technique.

Research highlights and achievements in the ongoing projects are as follows:

• Different polymer/gel electrolytes were synthesized and used in electrochemical supercapacitors. The supercapacitors were characterized by impedance spectroscopy, cyclic voltametry, etc. The Cole-Cole plots exhibited a purely capacitive circuit.
• The problem of force induced adsorption-desorption transition of a polymer chain at a liquid- solid interface, a problem which had been active since de-Gennes days, was investigated. In 2D, desorption as a function of temperature had been studied and found to increase with decrease in temperature. In 3D, a re-entrance? a desorbed phase changing to adsorbed phase and then to desorbed phase as a function of temperature had been found. Force induced unzipping transition of a double stranded DNA molecule had also been studied.
• Studies on laser induced freezing of colloids, with reference to the elastic properties, were reported using a Beowulf Cluster. Studies on deformation mechanisms of solids at different scale lengths, effect of disorder on coarse-grained materials and solid-liquid interface had been carried out.
• Ferrofluids having seven different composition of nanomagnets, five carrier liquids and six coating materials including biomolecules had been synthesized and characterized. These fluids would be useful for seal, sensors, energy conversion and biotechnological applications.
• Temperature dependent micro Raman studies of orthorhombic CaFeO₃ and rhombohedral La_0.33Sr_0.67FeO₃ had been carried out. Raman Scattering experiments had also been carried out on Ca₂₊ substituted PbTiO₃ and single crystal of Nd_0.5Sr_0.5MnO₃. Apart from these, detailed high pressure Raman studies had been done on double walled carbon nanotubes, boron nitride multiwalled nanotubes and hexagonal boron nitride. Motivated by the experimental demonstration of the actuator action of single-walled carbon nanotubes, and in situ resonance Raman experiments, ab-initio restricted Hatree-Fock calculations of the electronic structure of (5,5) single walled nanotubes in the presence of various ions had been performed. The presence of ions near the nanotube caused combined axial and radial deformations of the nanotube. The presence of ions also caused small charge transfer from the ions to the nanotubes as well as changes in the ð- ð overlap energy (³).

Plasma, High Energy, Nuclear Physics, Astronomy & Astrophysics and Nonlinear Dynamics

New projects supported during the year were :

• Analysis of QSO Absorption lines Nature,
• Statistics and Chemical Enrichment;
• Intermediate energy nuclear reaction cross sections and production and study of exotic nuclear states;
• Plasma diagnostics in synthesizing c-BN by inductively coupled Plasma CVD;
• Structure of nuclei at high spins;
• Theoretical observations on nonlinear coherent structures of plasma acoustic waves in space (application to astrophysical problems);
• A study of hydromagnetic instabilities of plasma;
• Physics beyond the Standard Model in collider experiments;
• Self-focusing/defocusing of electromagnetic beams in ionospheric plasma and its effect on nonlinear processes;
• Novel approaches to low-energy strong interactions;
• Search for pulsations in chemically peculiar stars;
• Radiative transition probabilities and anomalous absorption of molecules in cool cosmic objects;
• The emergent dynamics and structure of networks; and
• Plasma behaviour at nano-dimensions; Exotic nuclei: structure and reaction studies.

A special initiative was taken to evolve programmes involving an integrated approach to multi wavelength astronomy. A Young Astronomers Meet was organized at IUCAA, Pune to bring together Ph.D. students working in various institutions in the country in Astronomy and Astrophysics.

An international Linear Collider Workshop was organized at IISc, Bangalore. Another international conference on Computing in High Energy Physics was also organized at TIFR, Mumbai.

Achievements from ongoing projects are as follows:

• In a project at NPL, New Delhi, a working facility for depositing a-Si:H films by PECVD technique had been set up. Uniform deposition rates across a 4" substrate had been achieved. Parametric studies on deposition, based on various parameters like H2 & Ar pressure, RF power (10 to 100 W) under VHF plasma conditions had been carried out and various electrical and optical techniques had been used to characterize the deposited films. An interesting observation of band gap variation (increase) from 2.3 to 2.8 eV with increase of RF power from 20 to 100W had been made. Much lower activation energy (0.6 to 0.3eV), compared to what was normally observed in a-Si:H films, was also reported.
• The Punjab University, Chandigarh group had made significant contributions as part of the BELLE Collaboration at KEK, Japan.
• The Delhi University group had made notable contributions in several areas of the D0 experiment at Fermilab, USA, for example, on ttbar production cross section in the di-electron channel and prompt photon production. The group had also made important contributions in detector monitoring and development of calibration procedures. Their efforts towards Bs mixing measurement were commendable. This was a very difficult measurement and the experience, thus gained, would be extremely useful to exploit the full potential of CMS data expected from LHC, where the group was also involved.
• At Berhampur University, the Deformed Configuration Mixing Shell Model with Isospin Projection had been used to study the structure of collective T=0 and T=1 bands in the odd-odd N=Z nuclei ⁴⁶V and ⁵⁰Mn. The pf-shell KB3 interaction had been employed in the calculation. The results compared well with the experiments.
• At IIT, Madras studies were conducted on squeezed states of radiation (coherent and photonadded coherent states) and evolution of entanglement in a quantum dynamical system.
• At Punjab University, Chandigarh, the Skyrme Energy Density formalism had been applied to the case of fragment (light and intermediate mass) emission from a hot compound nucleus. Temperature effects had been incorporated in the energy density formalism. Also, the dynamical collective clusterization model had been introduced in the treatment of fragment pre-formation. Though similar to the Statistical Model in spirit, it had new features like T dependence and dynamics in fragment formation/emission.
• At IIT, Kanpur, a ps laser ablation facility had been set up and extensive characterization of the plasma had been carried out through OES, fast photography, computer simulation, etc. on Al, C, Ti, Si and Zn plasmas. Some of the interesting results included the observation of AlN band, occurrence of R-T instability at the plume edge, estimation of self-generated B field and 2-4 nm sized Si clusters. The possibility of optical guiding was being explored.

Lasers, Optics, Atomic and Molecular Physics

New projects sanctioned are:

• Study of ultra-intense laser interactions with matter envisages experimental investigation of interactions of high-intensity (upto 1019 Wcm-2) ultra-short (upto 30 femto second) laser pulses with isolated molecules, clusters and solids.
• Classical simulation of ion-ion/atom interactions would be carried out and its chaotic behavior at low energies would be studied.
• Studies of non-radiative components and, hence, excited state photoprocesses in homogeneous and microheterogeneous environments through laser induced optoacoustic spectroscopy (LIOAS).
• Development of novel photorefractive polymers for optical recording with the aim to design and develop new chiral polymers and polymeric composites for optical recording, by carrying out measurements of diffraction efficiency, field-induced poling etc. and actual recording of holographic gratings on these.
• Studying laser driven ion coulomb explosion of clusters and plasma channels.
• Performance characteristics of optical fibres under proper dispersion management, including the effect of non-linearities, for a DWDM transmission system.

Research highlights and achievements in the ongoing projects are as follows:

• At BHU, Varanasi, a number of glasses with different glass formers (borate, oxyfluoroborate, calibo, tellurite etc.) had been prepared with different concentrations of the rare earth ions (Eu³⁺, Dy³⁺, Sm³⁺, Ho³⁺, Pr³⁺) and their absorption, fluorescence and excitation spectra had been studied.
• At IIT, Delhi, laser-induced etching of GaAs and Cr-O doped GaAs had been studied A model based on quantum effects had been developed to determine the size of nanoparticles. Transport and optical properties change drastically in quantum confined structures in comparison to bulk and crystalline structure.
• Quantum information processing had been achieved up to 5-qubits at IISc, Bangalore. It had been demonstrated that for both quadrupolar and dipolar coupled spin ½ nuclei, where individual spins could not be treated as individual qubits, they could be collectively treated as multi-qubit systems. The spin 7/2 quadrupolar nucleus oriented in liquid crystal matrix had been treated as a 3 qubit system. Optimum labeling schemes had been developed for such a system. Various logic gates, preparation of pseudopure states, creation and transfer of entanglement had been demonstrated.
• At Pondicherry University, the conditions for exact soliton propagation with higher order linear and nonlinear optical effects had been examined. The effect of damping on NLS solitons and a given solution to compensate damping through initial phase modulation had been analyzed.