Raman Research Institute

Present investigation covers the dielec. and electro-optical study of nematic liquid crystal (NLC) 1823 A dispersed with the ferromagnetic nanoparticles (FNPs) Fe₃O₄.Three concentrations of nanoparticles (NPs) in the NLC matrix namely 0.1 wt/wt%, 0.3 wt/wt%, and 0.5 wt/wt% are prepared and perceptible changes in the various properties are compared with the pure NLC.Variation of dielec. permittivity (ε) with the variation of frequency and variation of temperature is studied.Dielec. permittivity ε) is just found to be decreased as we increased the concentration of NPs, which shows that the applied elec. field is less impactful on the prepared composites.It is also found that the dielec. permittivity (ε) is increased with the increase of temperatureBirefringence is found to be decreased with the increase in the concentration of the NPs which showed that the orientational order of NLC 1823 A is got to be disturbed due to the presence of the NPs.It is also shown that as the temperature is increased, birefringence is found to get decreased due to its approach toward isotropic phase.Threshold voltage is found to be decreased by 56.25% for the 0.3 wt/wt% and by 25% for 0.1 wt/wt% composite which are pretty good result in context of achieving the low power optical switching devices.The results achieved are tried to be explained on account of the interaction between NLC and NPs.

The asymmetric unit of the compound C20H20BrClO3 contains one independent molecule in which the aromatic rings are oriented at a dihedral angle of 83.30 (2)°. An intramolecular C—H...O contact generates a five-membered S(5) ring motif. In the crystal, C—H...O hydrogen bonds link the molecules through R12(6), R22(10), R22(14) hydrogen-bond motifs. The structure is consolidated by C—H...π interactions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (32.8%), C...H/H...C (28.1%), O...H/H...O (14.0%) Br...H/H...Br (12.5%) and Cl...H/H...Cl (10.6%) interactions.

A detailed time-resolved anal. of laser-produced plasmas (LPPs) is essential for understanding the effects of ambient gas on plasma characteristics.In this work, a nanosecond pulsed laser (1064 nm, 7 ns) generates LPPs from a tungsten (W) target, which is comprehensively analyzed using optical emission spectroscopy, laser plasma interferometry, shadowgraphy, and imaging.Measurements reveal that varying the ambient pressure in the 1.33 x 10³ Pa - 5.33 x 10⁴ Pa range significantly affects the plasma temperature, number d. and plume morphol.Spectral anal. reveals a strong correlation between number densities obtained from Stark broadening measurements of the H-alpha and W I lines.The interferometric method enables the study of plasma plume morphol. and retrieval of number densities even in the presence of strong continuum emission.D. maps obtained from interferometry show inhomogeneities.Shadowgraphy images show the expansion of shockwaves at different pressures, and they also reveal that the transition of plasma from non-collective to collective behavior occurs around 1 x 10⁴ Pa.Despite inhomogeneities, plasma remains in Local Thermodn. Equilibrium during the observed time window of up to 1 μs.Due to well-established Stark parameters and strong linear correlation with the W I line, the H-alpha line provides a more straightforward estimation of number densities in tungsten LPPs.