Annexure-i justification of Building funds

Nuclear Reaction Dynamics studies at National Accelerator Facilities:

Nuclear reaction dynamics studies will be continued and new experiments will be planned in the National accelerator facilities of Inter University accelerator centre (IUAC), BARC-TIFR accelerator facility and the variable energy cyclotron centre (VECC) at Calcutta. The upgrading of IUAC accelerator with LINAC booster and the new super conducting cyclotron of variable energy cyclotron centre will provide us some unique projectile target combinations in low and medium energy regime for reaction studies.

The department will be actively engaged in the fission dynamics studies at IUAC, New Delhi. A neutron array will be proposed at IUAC in collaboration with Delhi University, Panjab University and Karnataka University and it will come up in next few years. The group will be actively involved in designing this apparatus and proposing experiment the department will be a part of National Neutron Array Collaboration. An experiment using the LINAC beam of IUAC using a 16 neutron detector array was performed to understand the fission dynamics of the heavy nuclei. New experiments are already planned

Fusion barrier distribution studies through quasi-elastic scattering methods for heavy Nuclei will be performed at IUAC accelerator facilities.

We plan to initiate a research activity on Radiation detector fabrication ( Both Gaseous and scintillator based) detector at the newly constructed detector laboratory established under the DST-purse programme.

The planned new generation gas filled recoil separator (HYRA) at NSC will give us some opportunities to study fusion dynamics of heavy system. Once it comes up fusion experiments will be proposed for this facility.

B4. International Facilities:

Besides using the national accelerator facilities and the activities in house facilities the group is planning to start renew collaboration and active contacts with the international facilities like GSI at Germany, LNL at Italy and Argon National Lab in USA. The group is planning to join in the GSI future accelerator (FAIR) Collaboration. Faculty members will be involved in planning of the experiments and apparatus for this new FAIR Collaboration.

B5. X-ray Fluorescence Laboratory:

Photon-atom interaction and subsequent processes near the electron binding energies and applications:

Current activities : The laboratory is equipped with X-ray tube based intense photon source, ²⁴¹Am and ⁵⁵Fe radioisotope based photon sources and Low energy Ge detector, Si(Li) detector and recently procured Peltier-cooled detector. Peltier cooled X-ray fluorescence (XRF) spectrometer (AMPTEK Make, USA) consisting of 0.5 m Silicon Drift Detector (25 mm², 500 mm Be window), Digital pulse processor and MCA. The Peltier cooled EDXRF spectrometer has been installed. The spectrometer shows FWHM 130 eV at 5.89 keV Mn K X-rays. The data acquisition and analysis software has been loaded on PC/Laptop, which makes it capable for in-vivo field measurements. Geometrical set ups has been designed for use with (i) Mn K x-rays from the ⁵⁵Fe source and (ii) the K x-rays of various elements, viz., Se, Mo, Zr, Rh, Ag, Sn, and Gd elements excited by the 59.5 keV gamma ray from the ²⁴¹Am point source (100 mCi) (secondary excitation mode). The geometrical set up has been designed and fabricated using workshop facility available Department of Physics. The spectrometer can be used efficiently in the photon energy range up to 30 keV. The following measurements are being performed/planned using the detector set up: (a) Characterization of the Peltier cooled detector – Measurements of resolution as a function of energy, escape peaks and its theoretical modeling. (b) In-vivo field measurements for articles lying in the Museum are being planned. (c) Angular distribution of the L₃ subshell x-ray emission and the scattering cross-section measurements are being planned using this detector and secondary exciter source. Because of the small size, measurements at large angles approaching 180^o are possible and the solid angle corrections will be minimized. (b) The procurement of Microfocus XRF spectrometer is under process.

The following are the current investigations taken by the group:

1. 
   Study of Influence of resonant Raman scattering in the elemental analysis using X-ray emission based techniques. Contribution of near-edge processes (RRS and XAFS) to attenuation of the characteristic X-rays in various elements for the photon energies (E_in) in the region of respective K-shell/L_i subshell (i = 1, 2, 3) ionization threshold (B_K/B_Li). The observed alteration from the theoretical values is attributed to the X-ray Absorption Fine Structure (XAFS) for negative B_K/Li - E_in values, and the K-shell/Li subshell resonant Raman scattering (RRS) process for positive B_K/Li-E_in values. Systematic of the K-shell/L_i subshell RRS contribution to attenuation of the X-rays are discussed in terms of the respective oscillator density and fraction of electrons available in the K-shell/Li subshell Lorentzian profile of the attenuation element below E_in. Possible matrix effects in the energy dispersive x ray spectrometry due to RRS are also explored.
   

(b) Differential cross sections for Elastic scattering of 59.54-keV γ-rays in elements with 22 ≤ Z ≤ 92 at momentum transfer 0.4 ≤ x ≤ 4.7 Å⁻¹ . The measured differential scattering cross sections are compared with those based on the form-factor (FF) formalism and state-of-the-art S-matrix calculations to differentiate between their relative efficacies and to check angular-dependence of the anomalous scattering factors (ASF) incorporated as correction to the modified form-factor (MF).

(c) Alignment of the L₃ subshell (J = 3/2) vacancy states produced following photoionization in the L_i (i = 1–3) subshells of ₇₉Au, ₈₃Bi, ₉₀Th, and ₉₂U have been investigated through angular distribution of the subsequently emitted L₃ subshell x rays. The measurements were also performed for these elements to investigate the effects of external magnetic field (0.60 T) on the L₃ subshell x-ray emission.

(d) The EDXRF set up has been used in the following applications

(i) Heavy metal uptake studies by biomass of immobilized microorganisms

(ii) Heavy metal induced physiological alterations in Salvinia natans

(iii) Elemental analysis of ground water from different regions of Punjab state (India) using EDXRF technique and the sources of water contamination - Multielemental analysis of the ground water samples from different locations at the boundary between Hoshiarpur and Nawanshahr districts, and Bathinda district of Punjab state (India) was performed. These regions are known to be contaminated by selenium and uranium, respectively. The water samples were analysed using the Energy-dispersive X-ray fluorescence (EDXRF) technique. The water samples from surroundings of the coal-fired thermal power plant in the city and the industrial waste water draining into Sutlej river were also analyzed to investigate the possible sources of water contamination in Bathinda. Agrochemical processes in the water-logged agricultural areas with calcareous soils and use of phosphate fertilizers are favoured sources deterioration of ground water quality in Bathinda district.

(iv) Elemental analysis of some ceria-based synthesized catalyst particles is preformed to know the composition of the mixed oxides of some metals with gold. The possibility of the reversible transition from CeO₂ to Ce₂O₃ makes cerium oxide one of the promising materials. Mixed oxide catalytic particlas were synthesized by the research group of Dept. of applied Chemistry, ISM, Dhanbad.

(v) EDXRF set up has been used to study of uptake of selenium in different portions of chick pea plant i.e. seeds leaves stem and roots is performed. The research group at Department of Botany, Panjab University, has undertaken these investigations. The experiment was designed for application as phytoremidation.

(vi) Thickness determination of CNT (carbon nanotube) films deposited on Si/Glass substrate using the EDXRF set-up involving Mo anode x-ray tube with suitable absorber to reduce the bremsstrahlung and LEGe detector.

(vii) Qualitative and quantitative analysis of Eu³⁺ and Sm³⁺ ions doped ZnS nanocrystals synthesized at Nano-material research laboratory, Chitkara University, Punjab for the photo-catalytic degradation of environmental organic pollutants.

(viii) The analysis of the targets used for nuclear and material science experiments by the students from IUAC, New Delhi.
Future plans:

To establish a new Experimental set-ups – (i) a versatile tunable x-ray photon source covering a range of monochromatic photon energies up to 50 keV and high resolution Si(Li) detector with ultra thin window and Peltier-cooled portable detector. The set up is planned to be used for the (i) Rayleigh scattering measurements in various elements at incident photon energies close to the binding energies, (ii) Resonant Raman scattering (RRS) in the X-ray region has a rather chequered development and deserves attention to make it an important tool to study materials, (iii) Alignment of atoms following photoionzation - X-rays emitted in subsequent decay of the atomic vacancy states manifest this alignment through their anisotropic emission. Predicted to be small in magnitude - Maximum alignment can be observed following selective ionization of the corresponding subshell -minimizing CK transitions. The predicted alignment is yet to be confirmed quantitatively. (iv) Determination of Fluorescence and Coster-Kronig yields for the L and M-shells - by measuring intensity of the X-rays from each of the individual subshells following selective photoionization among its subshells and (v) Analytical Applications - diverse applications ranging from ultra-trace element analysis to surface characterization/depth profiling of thin films, multilayer structures, semiconductor wafers. This facility will cater to needs of many scientific and industrial users from the region.

B6. Hyperfine Interaction Studies:

The research group has been engaged in the measurement of Hyperfine Interactions i.e. measurement of nuclear electromagnetic moments of the excited states and electric and magnetic hyperfine fields in the magnetic and non-magnetic systems, using PAC (off-line) and PAD (In Beam) techniques. The present facilities include a PAC set up involving multi-BaF₂ Scintillators, a Closed Cycle Helium Refrigerator (10K-300K) and Argon Arc Furnace. In the PAC experiments, the activity of the sample cannot be increased beyond a certain level set by the signal-to-noise requirements, the only way to reduce the data collection time, especially for shorter lived radioactive samples, is to increase the efficiency of the spectrometer. The proposed PAC spectrometer with 6 conical LaBr₃ detectors and NIM based data acquisition system will be resulting in 30 coincidence spectra simultaneously, with optimised detector-sample geometries covering about 60% of the 4 solid angle and the system having excellent time resolution to resolve the fast interaction frequencies encountered in many experiments. Solid state physics with radioactive isotopes is a prospering and growing field. The established nuclear techniques based upon hyperfine techniques (like PAC, PAD, NMR, NQR, Mössbauer spectroscopy etc have clearly proven the enormous potential of using radioactive probe atoms to characterize defects and impurities in solids. To exploit radioactive probe atoms even more efficiently, implantation energies up to some MeV would be highly desirable. Numerous radioactive species have been employed in the past to attack problems involved with defects or impurities in metals, semiconductors and superconductors.

B7. Nuclear Physics (Theory) Group:

Theoretical nuclear physics group at Chandigarh is involved in studying the nuclear dynamics at low, intermediate and relativistic energies. The research topics undertaken are (a) Cluster radioactivity, (b) Fusion, (c) Multifragmentation (d) Nuclear flow and its disappearances, and (e) Particle production at intermediate energies. At low energy, the concern is on the problems of fusion and fission processes whereas at intermediate energies, the work is on the problems of multifragmentation, collective flow and its disappearance, differential flow, elliptic flow, and their connection with nuclear equation of state, rapidity and stopping of nuclear matter and thermalization reached in a reaction.  Efforts will be made to compare our theoretical predictions with experimental data. A dynamical cluster decay model is advanced for the formation and decay of hot and rotating compound nuclear formed in light heavy ion reactions. Calculations are made for the compound system ⁵⁶ Ni* and ¹¹⁶ Ba*. Studies are being done to include deformations and orientations degree of freedom to generalize proximity nuclear potential and the coulomb potential. Possible new reactions for synthesis of new and super-heavy elements are pursued.

(C) Condensed Matter Group:

C1. Experimental Condensed Matter

Solid state Physics is one of the thrust areas recognised by UGC under CAS. The experimental activities of this group involve materials which are important from applications point of view as well as those that lead to an understanding of basic properties of matter and materials. On-going work involves identification of materials suitable for opto-electronic devices, fabrication and characterisation of semi-conducting thin films and preparation and characterisation of carbon Nanotubes.

During the last decade, this group has made significant contributions in training graduate and post-graduate students as well as research personnel. They have picked up the latest techniques being used by academics, research organisations and industry. At any given point in time there are about 18 Ph.D. scholars, 3-4 M.Sc. students, 2-3 M. Tech. (Nano-science and nano-technology) students and 2-3 M.Phil. students working in these laboratories.

Carbon nanomaterials such as C₆₀ and carbon nanotubes (CNTs) are deposited as thin films on various substrates, irradiated with swift heavy ions at IUAC, Delhi, and characterized by various means. We have also set up an arc discharge unit which can produce C₆₀ as well as CNTs, and has been used mainly as a training equipment for M. Sc. and M.Tech (NSNT) project students. This apparatus is also a part of regular lab. Course for M. Tech. (NSNT). Magnetic properties of nanoparticles of Ni are being studied in collaboration with materials science group at Central Scientific Instrumentation Organisation, Chandigarh, a CSIR lab.

Future plans

Materials Preparation and Characterization:

For tailoring of material properties through careful modification of the chemical composition of the nanoparticle surface, it is desirable to have controlled methods of deposition of films on different substrates. We will use the CVD technique for the same, using diverse materials such as opto-electronic ones, organic semiconductors, microcrystalline Si, ZnO (making p-type ZnO is still a problem), CNTs, chalcogenide glasses and so on.

Organic hybrid thin film photovoltaics have already demonstrated their potential. Thin films of these materials (copper pthalocyanine etc.) will be deposited and photovoltaic devices will be made using these. Further, heterostructures of these materials will be made which can be used for the sensing of different gases. Keeping in view the growing interest in amorphous carbon (a-C), hydrogenated and nitrogenated a-C and nanocrystaline diamond as potential materials for high efficiency solar cell and electroluminescent devices, we plan to deposit their films using the CVD technique. Microcrystalline hydrogenated Si (Si:H) which is also recognized internationally as a promising material for the active layer of thin film solar cells, will be deposited using the MWCVD method. Biosensors will be made using this material for the rapid detection of organic (protein, nucleic acid etc) molecules.

Chalcogenide materials which have high crystallization rate, high thermal stability etc., will be studied from optical memory device point of view. The nature of the amorphous to crystalline transition is crucial to understanding the switching operation of phase change materials. Some of these materials are highly photosensitive and show light induced changes after irradiation, so these are very promising materials for use in guided wave devices and infrared telecommunication systems. The nonlinear behaviour will be studied by z-scan technique. The domains of interest for compounds based on ZnO and associated heterostructures are optoelectronics and spintronics. The high excitonic energy makes it a potential candidate for light emission applications. Light emission devices will be made from ZnO nanocrystalline thin films after we have deposited them using the CVD technique.

Device Development and Fabrication:

We plan to use photoluminescence (PL) studies for these thin films by measuring the PL spectra at different temperatures. The decay kinetics will be very useful for characterizing and selecting the materials from the device point of view. The phase transitions studies will be done using the differential scanning caloriemetry (DSC) technique. Vibration free table is required for the setting up of the experiments like Constant Photocurrent Measurements (CPM), Photothermal Deflection Spectroscopy (PDS), optical non-linearity using Z-Scan technique etc in the laboratory. The devices like waveguides, solar cells, Schottky diodes, heterostructures, LEDs will be prepared and characterized during this period. These facilities, apart from research uses, will be very useful for students of interdisciplinary courses such as nano-technology and advanced courses such as M.Phil. in materials science to enhance their job potential in different research organizations and industries.

Effect of passage of high energy charged particles on materials has been an active area of research. We have substantial work on swift heavy ions on C₆₀ thin films. We intend to carry out similar work on CNT thin films. We are developing techniques to deposit good thin film on various substrates. We have often M.Sc. and M. Tech. Project students working on this problem.

The CNT produced in our arc discharge apparatus needs to be concentrated and well characterized. Students of M. Tech. (NSNT) are being regularly given laboratory exercises on this method. We plan to use some chemical methods for concentration of CNTs. The STM in this lab is also being used by the students. Acquisition of an AFM will go a long way in helping training as well as research.

C2. Condensed Matter (Theory) Group:

Introduction

Solid state Physics is one of the thrust areas recognised by UGC under CAS. The computational activities of this group involve carbon nano-materials which form currently important area of research. On-going work involves study of properties of carbon nanotubes and clusters of metals and semiconductors using various techniques. We also study anharmonic properties especially in the context of shock wave propagation in materials.

A large number of Ph.D.s have been granted in these areas and a significant number of M.Sc. (project) and M. Tech. (Nano-science and nano-technology) student are working with this group.

Current Activities

The last decade has seen a huge interest in the properties of matter at nanometer scale. Today it is practically (and arguably) the most active area of research in Physical sciences.

Our work mainly consist of predicting/ confirming the structure, dynamics and thermal properties of various carbon materials and other nanosystems such as metal clusters, BN Nanotubes etc., using potential models. We are also using proprietary software to determine electronic structure of these systems. Beginnings have been made in nanofluidics.

Future plans

Our computational efforts are going to see a thrust in electronic structure calculations. This requires cluster computing for which the system needs to be acquired. We also need to do molecular dynamics simulations for which software has to be obtained. All of these are being planned to be included in regular teaching courses (e.g., 'simulation' course under NSNT, 'programming' course under M.Sc. and special paper on nanomaterials for M.Sc. Physics students).

(D) Mass Spectrometry and Geochronology Group:

The work Rb-Sr isotopic and geochronlogical studies on the granitc, gneissic rocks of Jaspa, Chhotadara and Manali areas of Himachal Pradesh is being pursued. Geochemical investigations for major elements on these rocks are being carried out.

(E) Molecular Spectroscopy Group:

The Molecular Spectroscopy group is working in the following areas:

1. 
   Porphyrins, which are biologically important molecule and found in heamoglobin, myoglobin, and cytochromes etc. Chlorophyll and Vitamin B₁₂ are also related compounds. We are studying chemical and photo-induced electron transfer processes in porphyrins and their gas sensing properties with the help of vibrational spectroscopic techniques and density functional theory calculations.
   
2. 
   Phthalocyanines: These are organic semi conductors and have many practical applications. We are studying their volatile organic chemical sensing properties by spectroscopic techniques and density functional theory.
   

Initially, we studied the effect of pyridine on the geometrical structure and vibrations of zinc phthalocyanine in order to understand the possible interactions of organic vapours molecules with the phthalocyanine molecules. We have used density functional theory calculations and infrared absorption spectroscopy for this purpose. X-ray diffraction pattern was also recorded in the absence and presence of pyridine. In the presence of pyridine phase of the crystalline zinc phthalocyanine changes from b to a. Some infrared bands show changes in their positions and/or intensities. These changes have been interpreted on the basis of coordination of the pyridine molecule with the central zinc ion. Coordinated pyridine transfers some of its charge to the p electron system of the phthalocyanine ring through zinc ion. Pyridine molecule also distorts the phthalocyanine molecule by pulling zinc ion out of the phthalocyanine plane. Density functional theory also confirms the ligation of pyridine molecule at the fifth coordination site of the central metal ion.

Next, we have studied zinc phthalocyanine thin film and chemical analyte interactions by density functional theory and vibrational techniques. For this purpose, thin films of zinc phthalocyanine were deposited on KBr and glass substrates by the thermal evaporation method and characterized by the x-ray diffraction, optical, infrared and Raman techniques. The observed x-ray diffraction and infrared absorption spectra of as-deposited thin films

suggested the presence of an a crystalline phase. Infrared and Raman spectra of thin films after exposure to vapours of ammonia and methanol had also been recorded. Shifts in the position of some IR and Raman bands in the spectra of exposed films were observed. Some bands also showed changes in their intensity on exposure. Increased charge on the phthalocyanine ring and out-of-plane distortion of the core due to interaction between zinc phthalocyanine and vapour molecules involving the fifth coordination site of the central metal ion might be responsible for the band shifts. Changes in the intensity of bands were

interpreted in terms of the lowering of molecular symmetry from D4h to C4v due to doming of the core. Molecular parameters and Mulliken atomic charges of zinc phthalocyanine and its complexes with methanol and ammonia had been calculated from density functional theory. The binding energy of the complexes had also been calculated. Calculated values of the energy for different complexes suggested that axially coordinated vapour molecules formed the most stable complex. Calculated Mulliken atomic charges showed net charge transfer from vapour molecules to the phthalocyanine ring for the most stable complex.

We have also studied the effects of chemical vapours on the vibrational spectra of nickel phthalocyanine thin films experimentally and theoretically by density functional theory. Effects of chemical vapours on the Raman and infrared absorption spectra of a crystalline nickel phthalocyanine thin films were reported. Transmission electron micrograph of the thin films suggested presence of nano-sized particles of nickel phthalocyanine in the thin film. Some vibrational bands showed changes in their positions and/or intensities on exposure of thin films with chemical vapours. These changes were interpreted on the basis of interactions of the vapours molecule with the central nickel ion and other peripheral atoms of the phthalocyanine ring. Density functional theory calculations were also carried out to determine the probable geometric structures of the complexes of vapour and phthalocyanine molecules. Calculated geometric structures showed in-plane and out-of-plane distortions in the phthalocyanine molecule. Calculations further suggested charge transfer between vapour

and phthalocyanine molecules. In contrast to zinc phthalocyanine, this molecule can form six coordinated species with vapour molecules.

We have also studied the sensing mechanism of zinc tetraphenylporphine (ZnTPP) towards the methanol, pyridine, diethylamine, dichloromethane, acetonitrile, bromine and NO2 vapours. We deposited thin films of ZnTPP and recorded the resonance Raman and infrared absorption spectra of thin films before and after exposure with diethyl amine/methanol vapours. Positions of some vibrational bands show detectable change on exposure. Changes

in the intensity of some vibrational bands of the thin films have also been observed on exposure. Coordination of vapours molecules at the zinc ion and subsequent charge transfer are responsible for the shift in the vibrational bands. Density functional theory calculations have been carried out to determine the probable geometric structures of the porphyrin-vapour complexes. Calculated geometric structures show in-plane and out-of-plane distortions in the porphyrin macrocycle. Calculations also result in charge transfer between vapour and porphyrin molecules.

3.