A study of the influence of the input electrical power on the spectral width of the 510.6 nm line of an atomic copper vapor laser

The effect of the input electrical power on the spectral width of the 510.6 nm line of an atomic copper vapor laser (CVL) is investigated. An analysis of the gas temperature inside the discharge tube and the line broadening mechanism of the CVL is reported. The input electrical power was varied from 2.0 to 4.2 kW in a cylindrical discharge tube of inner radius 2.35 cm and length 150.0 cm. A Fabry–Perot etalon and imaging camera-based setup interfaced with personal computer was used to measure the spectral width of the 510.6 nm (green) laser line. The Doppler broadened spectral profile of the laser emission varies with input electrical power and an additional broadening of almost 1 GHz at the highest operating input power was observed.     

Effect of indium intercalation on various properties of MoSe2 single crystals

Indium intercalated MoSe₂ single crystals i.e. In_xMoSe₂ (0 ≤ x ≤ 1) are grown by direct vapour transport technique. These crystals are structurally characterized by X‐ray diffraction, by determining their lattice parameters ‘a’ and ‘c’ and X‐ray density. The Hall effect and thermoelectric power measurements shows that In_xMoSe₂ (0 ≤ x ≤ 1) are p‐type in nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Pyrene functionalized oxacalix[4]arene architecture as dual readout sensor for expeditious recognition of cyanide anion

A pyrene functionalized oxacalix[4]arene architecture (DPOC) was utilized as a fluorescence probe for selective recognition of cyanide ions. The receptor DPOC shows excellent selectivity towards cyanide ion with a red shift of 108 nm in absorption band along with a significant change in colour from light yellow to pink. The fluorescence titration experiments further confirm the lower limit of detection as 1.7µM with no significant influences of competing anions. ¹ H-NMR titration experiments support the deprotonation phenomena, as the -NH proton disappears upon successive addition of cyanide ions. The DFT calculation also indicates a certain increment of -NH bond length upon interaction with cyanide ions. The spectral properties as well as colour of DPOC-CN^? system may be reversed upon the addition of Ag⁺/ Cu²⁺ ions up to 5 consecutive cycles. Moreover, DPOC coated “test strips” were prepared for visual detection of cyanide ions.

     

Study of Removal of Cationic Dye from Waste Aqua Using Chromatographic Grade Silica as Adsorbent

The adsorption of cationic dye, Basic Red 13 from aqueous solution onto silica has been studied. The time growth adsorption as a function of the amount of adsorbent, pH, initial dye concentration as well as the temperature was measured of the system. Adsorption was found to follow a first-order process. Various isotherm and thermodynamic parameters for the adsorption of dye have been calculated. Isotherms were used to identify formation of either monolayer or multilayer formation whereas thermodynamic and other parameter indicated that the dye adsorption process was physisoption as well as spontaneous and exothermic in nature.     

A composite (stacked) picture generation technique for spectral profile representation of dye laser

In this paper, a new technique for data representation format from video recording of spectral profile of tunable dye laser has been formulated. Only a part of the acquired images acquired sequentially in programmed time interval, was used to make the composite picture to measure variation of the parameters. A CCD camera based imaging system was used to confine the spectral pattern. No additional hardware other than image capturing device was used. The technique developed reduces the storage space required in the computer and also enhances the measurement speed significantly. The software algorithm developed has been used effectively to measure various parameters of tunable dye lasers and other optical sources.     

Superconducting state parameters of indium-based binary alloys

Our well-recognized pseudopotential is used to investigate the superconducting state parameters viz: electron-phonon coupling strength λ. Coulomb pseudopotential μ*, transition temperature T _c, isotope effective exponent α and interaction strength N ₀ V for the In_1−x Zn _x and In_1−x Sn _x binary alloys. We have incorporated six different types of local field correction functions, proposed by Hartree, Taylor, Vashistha-Singwi, Ichimaru-Utsumi, Farid et al and Sarkar et al to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange and correlation functions is concluded from the present study. The comparison with other such theoretical values is encouraging, which confirms the applicability of our model potential in explaining the superconducting state parameters of binary mixture.     

Synthesis and study of 4-(4'-n-alkoxybenzoyloxybenzoyl)-4'-n-butoxyanilides

Thirteen compounds with ester and amide linkages were synthesized and their mesogenic properties evaluated. Methyl to n-propyl derivatives exhibit nematic phases, n-butyl to n-decyl derivatives exhibit smectic and nematic mesophases, whereas n-dodecyl to n-octadecyl derivatives exhibit only smectic phases. All the smectic homologues exhibit smectic C phases. Middle members of the homologous series exhibit polymorphism of smectic mesophase. A plot of transition temperatures versus number of carbon atoms in the alkoxy chain reveals an odd-even effect for nematic-isotropic transition temperatures. Nematic-isotropic and smectic-cholesteric thermal stabilities of the prepared compounds (series I) are higher compared to those of previously reported compounds, series A, B and C. The results indicate that a simple reversal of a central linkage has a dramatic effect on the appearance of smectic mesophase in a homologous series. The structures of the synthesized compounds were characterized using elemental analysis, thin-layer chromatography and spectral data.     

On the coherence measurement of a narrow bandwidth dye laser

In this paper, we report a new technique for spatial and temporal coherence measurement of narrow bandwidth sources. In particular, coherence measurement of a narrow bandwidth dye laser using Young’s double slit method and the Fabry–Perot interferometer has been carried out. In the spatial coherence measurement, a central fringe visibility of 0.85 was observed, and from this measurement, the dye gain medium source size was estimated. The variation in the visibility with slit separation (0.1–3.0 mm) for different source sizes (0.1–0.2 mm) was also analyzed. The temporal coherence length of the tunable dye laser was measured to be 10 and 60 cm for multimode and single-mode operations, respectively. The technique, in general, can also be used for spatial and temporal measurement of broadband spectrum source.     

Induced Mesophases in Binary Systems of Non-Mesogens Where One of the Component is 1,2,4 Trisubstituted Benzene Derivatives

Abstract

Exhibition of mixed mesophases in binary systems where both the components are non-mesogens by themselves offer a very interesting study. In the present work four binary systems were studied where one of the components is non-mesogenic 1,2,4-trisubstituted benzene derivative while the other components are rod shaped non-mesogens. Induction of mesophases is observed in all the binary systems studied. Few compositions on cooling remain in liquid crystalline phase at the ambient temperatures for about 48 hours.     

New mesogens with a fluoro-substituted bent core

Ferroelectric properties in liquid crystals are no longer restricted to materials with a chiral molecular structure; ferroelectricity has been observed in a smectic phase formed by bent achiral molecules. Accordingly, two homologous series possessing a central biphenyl methane core have been synthesized, the central core having two lateral fluoro substituents. Both the series have six-ring structures and exhibit smectic mesophases of high thermal stability. The flexible biphenyl methane core imparts a slight curve to the molecules, giving them a bent shape.