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Magnetic susceptibility and electrical conductivity studies on the aqueous solutions of two nonionic surfactants
No full textRestricted Access.Mass diamagnetic susceptibility, AC and DC electrical conductivity studies on two nonionic surfactants (Triton X-100 and Brij-35) in water as a function of temperature for various concentrations of the surfactants are reported. It is found that in these systems, the susceptibility is directly related to the sizes of the micelles. The Arrhenius plots for AC conductivities showed marked slope changes at the cloud point (CP) for all the concentrations of Triton X-100. The activation energies are evaluated from these plots and found to be concentration dependent. Temperature dependence of DC electrical conductivity is found to be similar to that of the degree of hydration of these micelles
Extendend low density lonized gas in the inner galaxy : a study using recombination lines
No full textCollapse and coacervation of a lamellar phase by inter-headgroup bridging
No full textRestricted Access.We report the collapse of an electrostatically swollen surfactant lamellar phase above a critical concentration of an added nonionic surfactant due to hydrogen bonding between the two types of headgroups. At still higher concentrations of the neutral surfactant a temperature-driven lamellar to coacervate transition is observed. Small-angle X-ray diffraction pattern of the coacervate can be modeled as arising from bilayers with short-range positional correlations, whereas cryo-scanning electron microscopy images show bilayer-like features riddled with pores. Very similar behavior is found when the nonionic polyoxyethylene alkyl ether surfactant is replaced by polyethylene glycol of sufficiently high molecular weight
Classical light analogue of the non-local Aharonov-Bohm effect
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We demonstrate the existence of a non-local geometric phase in the intensity-intensity correlations of classical incoherent light, that is not seen in the lower-order correlations. This two-photon Pancharatnam phase was observed and modulated in a Mach-Zehnder interferometer. Using acousto-optic interaction, independent phase noise was introduced to light in the two arms of the interferometer to create two independent incoherent classical sources from laser light. The experiment is the classical optical analogue of the multi-particle Aharonov-Bohm effect. As the trajectory of light over the Poincaré sphere introduces a phase shift observable only in the intensity-intensity correlation, it provides a means of deflecting the two-photon wavefront, while having no effect on single photons
Moments of non-Gaussian Wigner distributions and a generalized uncertainty principle: I. The single-mode case
No full textRestricted Access.The non-negativity of the density operator of a state is faithfully coded in its Wigner distribution, and this coding places on the moments of the Wigner distribution constraints arising from the non-negativity of the density operator. Working in a monomial basis for the algebra of operators on the Hilbert space of a bosonic mode, we formulate these constraints in a canonically covariant form which is both concise and explicit. Since the conventional uncertainty relation is such a constraint on the first and second moments, our result constitutes a generalization of the same to all orders. The structure constants of , in the monomial basis, are shown to be essentially the SU(2) Clebsch–Gordan coefficients. Our results have applications in quantum state reconstruction using optical homodyne tomography and, when generalized to the n-mode case, which will be done in the second part of this work, will have applications also for continuous variable quantum information systems involving non-Gaussian states
Plasmonic, low-frequency Raman, and nonlinear optical-limiting studies in copper-silica nanocomposites
No full textRestricted Access.Nanocomposite thin films consisting of Cu nanoparticles embedded in silica matrix were synthesized by atom beam co-sputtering technique. Plasmonic, optical, and structural properties of the nanocomposite films were investigated by using ultraviolet (UV)-visible absorption spectroscopy, nonlinear optical transmission, X-ray diffraction (XRD), and low-frequency Raman scattering. UV-visible absorption studies revealed the surface plasmon resonance absorption at 564 nm which showed a red shift with increase in Cu fraction. XRD results together with surface plasmon resonance absorption confirmed the presence of Cu nanoparticles of different size. Low-frequency Raman studies of nanocomposite films revealed breathing modes in Cu nanoparticles. Nanocomposites with lower metal fractions were found to behave like optical limiters. The possibility of controllably tuning the optical nonlinearity of these nanocomposites could enable them to be the potential candidates for applications in nanophotonics
Textured domains on tense surfaces and membranes: Effect of tilt and chirality
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We study the shape and texture of finite domains comprising chiral or achiral molecules carrying tilt, embedded in a two-dimensional surface or membrane, using a combination of simulations and exact variational calculations. We find a variety of shapes and textures including rectangular-shaped domains and a spontaneously broken chiral texture, when the molecules are achiral. We show that chiral tilt domains nucleating in a region of two-phase coexistence repel each other, thereby preventing coalescence and further growth. Our work principally addresses observations of domains in multicomponent giant unilamellar vesicles. It may also be relevant in the study of domains in phospholipid monolayers, nucleating domains of Sm-C* in Sm-A films, and chiral emulsions in Sm-A films, in situations where we can ignore dipolar interactions