Annual Report 1999-2000

Autonomous Institutions

Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore

The main objectives of the Centre in fostering, promoting and sustaining the cultivation of sciences and scientific research in all its aspects - pure, applied and educational, continued to be the central point of its activities during the period under review.

Under the Summer Research Fellowship Programme 100 Fellowships were utilised by students across the country. The Ph.D. programme has steadily expanded, where nearly 40 students are working for their Ph.D. degrees in front-line research areas. A new programme M.Sc.(by research) is proposed to be introduced from the academic year 1999-2000 for the benefit of professional course students.

During the period under report the extension programmes of the Centre included 30 Discussion Meetings in the frontier areas of science and technology, 7 lectures including two special lectures - one on Synthetic antigenes to Synthetic vaccines against infectious and autoimmune diseases and another on Mathematics at the Turn of the Millennium - 14 colloquia and 32 semi nars on subjects relating to Genetics, Biodiversity, Evolutionary and Organismal Biology, etc. A total of 20 Visiting Scientists visited the Centre during the year. Two scientists from China availed the Fellowships under the ICTP Programme, 5 scientists from Nigeria, Nepal and Egypt participated under the COSTED Programme and 1 scientist under the INDO-Kazakastan Programme visited India for varying periods.

The Centre continues its research activities in various units and several new lines of research are being launched. A total of 248 research publications were published. The Centre has also under its umbrella 14 sponsored projects involving national and international collaboration on subjects crucial to the development of science and technology in India and abroad.
Raman Research Institute, Bangalore

The Raman Research Institute founded by Prof. C. V. Raman in the late forties was reorganised, after his death in 1970, as a national Institute for research in basic science and it has been receiving grants from the Department of Science and Technology of the Government of India since 1972. The main fields of research are Theoretical Physics, Optics, Liquid Crystals and Astronomy & Astrophysics.

Theoretical Physics

In the area of Quantum Gravity and Black holes the following research is in progress:

• The analysis of the back reaction of Hawking radiation in simplified toy models of black holes coupled to quantum scalar fields in 2 dimensions. This problem is being studied using the closed-time-path (CTP) effective action method. The identification and interpretation of fluctuation and dissipation kernels of the effective action for various boundary conditions is in progress.
• Spin foam quantization of the Husain-Kuchar model: We are studying this diffeomorphism invariant model by "covariant loop quantization".
• Interpreting Black Hole Entropy: This work concerns the physical interpretation of black hole entropy. The approach followed here is to work on the space of solutions to Einstein’s equations.

In the area of Gravitational Radiation and numerical relativity research is in progress:

• The refined balance procedure to constrain the reactive acceleration is further generalised to explore the effects of linear momentum flux on the motion of the centre of mass of the binary. This should impose restrictions on the individual accelerations of the two bodies of the compact binary moving on general orbits. The analysis at the 2.5PN order is complete and work on the 3.5PN order is under investigation.
• Setting up 1D GR-Hydro code and 3D code ‘CACTUS’: Evolution of Einstein field equations becomes necessary while studying the collision of two black holes, merger of neutron stars, black holes and the collapse of very massive objects. Since the field equations are a set of coupled non-linear partial differential equations, often the studies of above systems rely on stable and efficient numerical codes. We propose to use these studies in the future.

In the area of optics the following work is in progress:

• The question of if and how Optical Bistability affects the establishment of correlations among the atoms, in particular whether atomic squeezing is enhanced near the bistability threshold is being investigated.
• Studies on wave propagation in random media (active and passive) are in progress. The combined effects of order and disorder are also being investigated.

In the area of Condensed Matter Physics, the following work is in progress:

• The role of inter-layer tunnelling and its blocking by intra-layer scattering in high Tc superconductivity.

Optics

• Light Scattering Studies
  • Experiments and Monte Carlo calculations on the back-scattering patterns in turbid media, that were started some time ago, were completed. The origin of these patterns has now been explained. The scattering intensity profiles have been quantitatively derived, making it possible to use these patterns for remote characterisation of scattering media.
  • The study of quasiballistic photons in turbid media by experiments and numerical simulations has also been brought to conclusion. The conversion of ballistic photons to diffusive has been studied, and some inadequacies of the diffusion theory highlighted.
  • The phenomenon of "mirror less lasing" in random amplifying media have been studied both experimentally by Monte-Carlo simulations. The experimentally observed features have been explained in terms of a simple model involving stimulated emission and self absorption.
  • Experiments are planned to image through biological turbid media using low power continuous wave light sources.
  • Light propagation in random amplifying media will be studied, with emphasis on the coherence properties. Two and one-dimensional systems will also be studied.
• Laser Cooling and Trapping
  • Fluorescence has been observed in rubidium vapour. Work is now in progress for frequency stabilisation by saturated absorption.
  • Frequency locking of the external cavity diode laser, injection locking of other slave lasers, and formation of a cold cloud are expected to be achieved shortly.

Liquid Crystals

• Many new compounds with banana shaped molecules have been synthesised in the chemistry laboratory. Some of them exhibit novel liquid crystalline phases. Extensive physical studies including binary phase diagrams of these compounds with other types of liquid crystals, also synthesised in our laboratory, have been taken up and there are indications that new types of phase diagrams may be exhibited in some of the mixtures.
• An optical set up to measure the path difference of liquid crystals under high pressures has been fabricated. An experimental set up, which includes an index matching cell, temperature controller, etc., has been fabricated to conduct dynamic light scattering studies on the viscoelastic modes of cholesterics.
• Theoretical investigations of the non-linear optical effects on the structure and properties of liquid crystals have been taken up to find a rich phase diagram of structural transitions.
• Theoretical investigations on the structure and energetics of the Twist Gain Boundary A (TGBA) has been undertaken to evaluate the structural parameters characterising such liquid crystals. Theoretical investigations on the stability of the Undulating TGBc* phase discovered earlier in our laboratory have also been carried out.
• A preliminary electron density map of the metastable symmetric ripple phase of DPPC has been calculated. Addition of even small amounts of polymers has been found to produce a dramatic decrease in the viscosity of surfactant solutions, which have rod like micelles.
• A successive approximation method has been developed for displaying grey shades in RMS responding liquid crystal displays. The brightness uniformity of pixels has been improved by introducing a dead time between selection of two successive rows in the line by the addressing technique.
• Studies on the kinetics of adsorption of alkanethiols on gold, silver and copper surfaces have been conducted using electrochemical impedance spectroscopy to measure the extent of monolayer coverage.
• The synthesis of novel types of liquid crystalline compounds will be continued. The physical studies on some of them, in both pure form and binary mixtures will be pursued to look for novel properties. The high-pressure set up will be used to study the effect of pressure on nematic-nematic transition in highly polar compounds, and other phase transitions involving liquid crystals.
• Dynamic light scattering studies will be taken up on cholesterics to investigate the twist and umbrella modes as functions of helical pitch and temperature. Theoretical investigations will be carried out on the effect of gradients in helical pitch on the diffraction pattern of non-uniform cholesterics in the phase grating mode. Monolayer studies on novel mesogenic molecules will be taken up.
• Theoretical studies on the effect of non-linear optical fields on structural and optical properties of chiral liquid crystals will be continued. The suppression of director fluctuations by the laser field will also be investigated.
• Refinement of the electron density map of the ripple phase of DPPC will be carried out. Quantitative studies on the influence of polymers on the structure and physical properties of micellar solutions will be taken up.
• The theoretical investigations on the structure and energetics of TGB phases will be further elaborated. Investigations on the effect of chiral polymers on fluid membranes will be taken up to understand some available experimental results.
• Theoretical investigations on the electric and magnetic field induced instabilities of nematic liquid crystals will be continued.
• A hardware implementation and verification of the successive approximation technique for generating grey shades in LCDs will be taken up. Work on implementation of new addressing techniques for restricted patterns will also be initiated.
• The STM built in the laboratory will be used to study adsorption of organic molecules on gold surfaces to look for self-assembling structures. An STM specifically meant for electrochemical studies will also be developed.

Astronomy & Astrophysics

• Observations of clusters of galaxies with the GMRT (Giant Metre Wavelength Radio Telescope) of TIFR at Pune were carried out. The 21-cm system (built at the Institute) performed to its expected technical specifications. Observations of the interstellar medium of our own Galaxy were carried out using the same system.
• The processing of the data from the Mauritius Radio Telescope was continued, extending the right ascension coverage and standardising the procedures.
• The system built at the Radio Astronomy Laboratory (RAL) of RRI for observations of pulsars with the GMRT at Pune was put through a technical commissioning phase and has performed as per the design. Preliminary astronomical data have been taken and are being analysed.
• Data of several radio pulsars taken at low frequencies are being analysed to reveal pulse to pulse fluctuations, and investigate the nature of the emission. X-ray and other data have been given new constraints on the astrophysics of neutron stars in binary systems. Implications for the internal structure have been worked out.
• The use of the GMRT for observations of external galaxies and of our own Galaxy will increase. The data already gathered will be processed and interpreted in terms of astronomical parameters such as the physical state and motions of gas in the galaxy, the evolution of galaxies in clusters, etc.
• Studies of the polarisation properties of radio pulsars with the new system built and commissioned by the RAL are planned.
• The on-going studies of neutron stars in binaries will be extended to include implications for stellar evolution of the progenitors and the evolution of the magnetic fields of the neutron stars.
• On-going work on the intergalactic medium, especially its heating, cooling and cosmic evolution will be continued.
• The mapping of the sky at a wavelength of two metres with the data already obtained by the Mauritius Radio Telescope is expected to reach an advanced stage.
• Receivers and correlators for carrying out Very Long Baseline Interferometry (VLBI) of methanol masers will be developed.
• The high-speed digital correlator for radio spectral line observations is proposed to be commissioned.