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Langmuir and Langmuir-Blodgett (LB) films of nonamphiphilic 2-(4-Biphenylyl)-5 phenyl-1,3,4- oxadiazole (abbreviated as PBD) mixed with stearic acid (SA) as well as also with the inert polymer matrix poly(methyl methacrylate) (PMMA) have been studied. Surface pressure versus area per molecule (-A) isotherms studies suggest that PBD molecules very likely stand vertically on the air-water interface and this arrangement allows the PBD molecules to form stacks and remain sandwiched between SA/PMMA molecules. At lower surface pressure phase separation between PBD and matrix molecules occur resulting due to repulsive interaction. However at higher surface pressure PBD molecules form aggregates. The UV-Vis absorption and Steady state fluorescence spectroscopic studies of the mixed LB films of PBD reveal the nature of the aggregates. H-type aggregates predominates in the mixed LB films whereas I-type aggregates predominates in the PBD-PMMA spin coated films. The degree of deformation produced in the electronic levels are largely affected by the film thickness and the surface pressure of lifting.
Frenkel excitons, the primary photoexcitations in organic semiconductors that are unequivocally responsible for the optical properties of this materials class, are predicted to form emph{bound} exciton pairs, i.e., biexcitons. These are key intermedi
Erythrosiderites with the formula A2FeX5H2O, where A = Rb, K, and (NH4) and X = Cl and Br are intriguing systems that possess various magnetic and electric phases, as well as multiferroic phases in which magnetism and ferroelectricity are coupled. In
In a recent work, new two-dimensional materials, the monolayer MoSi$_{2}$N$_{4}$ and WSi$_{2}$N$_{4}$, have been successfully synthesized in experiment, and several other monolayer materials with the similar structure, such as MoSi$_{2}$As$_{4}$, hav
Measurements of the anisotropic properties of single crystals play a crucial role in probing the physics of new materials. Determining a growth protocol that yields suitable high-quality single crystals can be particularly challenging for multi-compo
An early study of saturated 4He film flow instability is revisited in view of recent theoretical work by Hiromitsu Takeuchi et al. (arXiv:0909.2144v1 [cond-mat.quant-gas] Sept. 2009). I show additional data that suggests a qualitative agreement with this theory and discuss the experimental details.