Parametric instability of dust lattice waves in a turbulent plasma sheath

It is shown that dust lattice waves (DLWs) become parametrically unstable in a turbulent dusty plasma sheath that contains random-phase ion plasma waves. Physically, the parametric instability arises because of the nonlinear coupling between ion plasma waves and DLWs. The parametric instability is identified as the possible reason for the observed "sublimation" transition of the plasma crystal from a solid to a gaslike state.     

Spontaneous generation of self-organized solitary wave structures at earth's magnetopause

Spontaneous formation of solitary wave structures has been observed in Earth's magnetopause, and is shown to be caused by the breakup of a zonal flow by the action of drift wave turbulence. Here we show matched observations and modeling of coherent, large-scale solitary electrostatic structures, generated during the interaction of short-scale drift wave turbulence and zonal flows at the Earth's magnetopause. The observations were made by the Cluster spacecraft and the numerical modeling was performed using the wave-kinetic approach to drift wave-zonal flow interactions. Good agreement between observations and simulations has been found, thus explaining the emergence of the observed solitary structures as well as confirming earlier theoretical predictions of their existence.     

Anomalous reflection and excitation of surface waves in metamaterials

We consider reflection of electromagnetic waves from layered structures with various dielectric and magnetic properties, including metamaterials. Assuming periodic variations in the permittivity, we find that the reflection is in general anomalous. In particular, we note that the specular reflection vanishes and that the incident energy is totally reflected in the backward direction, when the conditions for resonant excitation of leaking surface waves are fulfilled.     

Fabrication of nanopatterned germanium surface by laser-induced etching: AFM, Raman and PL studies

Fabrication of the nanopatterned germanium (Ge) surface is done by laser-induced etching. Atomic force microscopy is utilized here to study the surface and sizes of Ge nanoparticles. Raman and photoluminescence (PL) spectroscopy have been used to characterize their vibrational and light emission properties. Wavelength-dependent Raman investigations of these nanopatterned Ge surface reveal spatial distribution of sizes of nanoparticles. Nanopatterned Ge structures (etched for 60 min) emit a broad PL band having two maxima at 2.1 and 2.35 eV.     

Dielectric studies in dilute solutions

Dielectric studies in dilute solutions of cyclohexane and benzene have been carried out in the temperature range 294–318°K. The observed data have been utilized to evaluate the relaxation times and thermodynamic parameters of these molecules. The high values ofα for 2-acetyl pyridine indicate the occurrence of more than one relaxation time. In the remaining systems, the observed lowα values indicate their rigid behaviour. The variation in the dielectric relaxation time is mostly correlated with the change in the heterocyclic configuration of the system.     

Atomic static multipole polarizabilities

Rivail and Rinaldi's scheme to work out the quantum static multipole polarizabilities have been extended to recover convergence in it. Our expressions give exact static multipole polarizabilities for the atomic hydrogen and give reasonable values for He-sequence.     

On the equivalence of angular force for lattice dynamics of b.c.c. metals

All angular force models developed for the study of lattice dynamics of b.c.c. metals are bound to give identical results. The recent model of Rani and Gupta is not an exception from this rule.     

Theory of interfacial phase transitions in surfactant systems

The spin-1 Ising model, which is equivalent to the three-component lattice gas model, is used to study wetting transitions in three-component surfactant systems consisting of an oil, water, and a nonionic surfactant. Phase equilibria, interfacial profiles, and interfacial tensions for three-phase equilibrium are determined in mean field approximation, for a wide range of temperature and interaction parameters. Surfactant interaction parameters are found to strongly influence interfacial tensions, reducing them in some cases to ultralow values. Interfacial tensions are used to determine whether the middle phase, rich in surfactant, wets or does not wet the interface between the oil-rich and water-rich phases. By varying temperature and interaction parameters, a wetting transition is located and found to be of the first order. Comparison is made with recent experimental results on wetting transitions in ternary surfactant systems.This paper is dedicated to J. K. Percus in honor of his 65th birthday.     

Magnetostatic mode in a sheared magnetic field

The effect of magnetic shear on the magnetostatic mode is considered. It is found that the lifetime of the mode is shortened, leading to a reduction of the corresponding cross-field diffusion.