Raman scattering investigation of the orientational dynamics of methyl iodide

A Raman scattering study of the v₃ vibration—rotation band in methyl iodide as a function of temperature and dilution (in cyclohexane) has been performed. All the data satisfy the second moment criterion. Detailed information about rotational correlation function, angular velocity correlation function, various correlation times and mean-square torque has been obtained. The correlation function, in the pure liquid, decays slowly with decrease in temperature whereas it decays faster with decreasing concentration in cyclohexane. It has been shown, from a consideration of the second moment as a function of concentration, that the contribution of collision-induced scattering to the v₃ band of methyl iodide is negligible. Applicability of a simple “damped librator model”, with a view to understanding certain aspects of the rotational motion in methyl iodide, is discussed.     

Retro-Claisen condensation versus pyrrole formation in reactions of amines and 1,3-diketones

Cyclic amines and 1,3-diketones readily react under microwave irradiation to form ring-fused pyrroles in a single operation. A competing retro-Claisen pathway is efficiently suppressed by employing p-toluenesulfonic acid as an additive.     

Effect of substrate texture on the growth of hematite nanowires

The effect of texture of iron foil substrate on the growth of hematite nanowires by annealing method has been investigated in detail. Three substrates of different textures were prepared from a [2 0 0] oriented iron foil by some simple processes. The hematite nanowires on these substrates were synthesized by annealing iron foil at 700 °C in moist oxygen. The growth pattern of nanowires on these substrates showed that the growth of hematite nanowires depends strongly on the iron substrate texture and [1 1 0] oriented iron grains are necessary for their growth. The samples were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), Electron Back Scatter Diffraction (EBSD) and Raman Spectroscopy. We have also tried to explain the various observations on the mechanism of growth. Mainly, the presence of water vapor significantly enhanced the formation of hematite nanowires which resulted in a very dense and aligned growth of nanowires on the substrate areas of favorable texture. Finally, the study proved the substrate texture to be a powerful tool to control growth of nanowires and can be used efficiently for patterning and large scale synthesis of the nanowires.     

Azimuthal correlation and fractal study of compound hadrons (pions and protons) at Dubna and SPS energy

This paper presents an investigation of compound hadrons (pions and protons) distribution emitted from ²⁴Mg-AgBr and ¹²C-AgBr interactions both at 4.5 AGeV and ³²S-AgBr interactions at 200 AGeV. The study includes azimuthal correlations (two particle and three particle), azimuthal asymmetry and fractal behaviour. This paper reveals some interesting results.     

Time-dependent quantum fluid density functional theory of hydrogen molecule under intense laser fields

A time-dependent generalized non-linear Schr?dinger equation (GNLSE) of motion was earlier derived in our laboratory by combining density functional theory and quantum fluid dynamics in three-dimensional space. In continuation of the work reported previously, the GNLSE is applied to provide additional knowledge on the femtosecond dynamics of the electron density in the hydrogen molecule interacting with high-intensity laser fields. For this purpose, the GNLSE is solved numerically for many time-steps over a total interaction time of 100 fs, by employing a finite-difference scheme. Various time-dependent (TD) quantities, namely, electron density, ground-state survival probability and dipole moment have been obtained for two laser wavelengths and four different intensities. The high-order harmonics generation (HHG) is also examined. The present approach goes beyond the linear response formalism and, in principle, calculates the TD electron density to all orders of change. Dedicated to Prof. D Mukherjee on his 60th birthday     

Helium atom in intense and superintense laser fields: A new theoretical approach

A quantum hydrodynamical study is made of the dynamical changes of a helium atom interacting with lasers of two different intensities, but having the same frequency. Under the intense laser field, electron density oozes out of the helium atom by absorbing laser photons and getting promoted to higher excited states including the continuum. Under the superintense field, electron density partly moves away from the helium nucleus but remains in the “quasi-bound” dressed states along with the laser field, thus suppressing ionization.     

Study of transfer of trace elements from soil to medicinal plants in the environment of Mangalore

The concentration of five trace elements Cr, As, Pb, Rb and Sr in seven medicinal plants Garcinia indica, Ficus benghalensis, Flacartia Montana, Nyctanthes arbor-tristis, Morinda citrifolia, Ficus recemosa, Barringtonia acutangula and associated soils were analyzed using ICP-MS. In plant the elemental concentrations of Cr, Pb, Rb and Sr vary widely and in soil the elemental concentrations of Cr, As and Sr showed wide variation. Selective enrichment of elements Rb and Sr was observed in some plants. The soil to plant transfer ratio was significant for Sr. The results of these systematic investigations are presented and discussed in this paper.     

Patterning of sol gel thin films by capillary force assisted soft lithographic technique

Patterning of sol gel based silica and silica–titania films has been developed at room temperature by soft lithographic technique. Corresponding metal alkoxides have been utilized for the preparation of precursor sols. Elastomeric stamps of polydimethylsiloxane (PDMS) are used to emboss patterns of a master grating on the as-prepared silica and silica–titania films obtained by sol gel process. Pressure-less capillary force lithography has been used to fabricate both 1-D and 2-D ordered structures of simple stripe patterns. A modified solvent assisted lithography and micro-molding in capillaries yielded stable and high fidelity 1-D structures for silica and silica–titania films over a large area.