Electron energy-loss cross sections for the chemical bond overlap plasmon Of the hydrogen molecule

We examine the possibility of detecting the chemical bond overlap plasmon (CBOP) of the hydrogen molecule by electron inelastic scattering. The CBOP has been predicted to efficiently absorb and scatter electromagnetic radiation above the molecular ionization threshold in the cases of alkali halides. For the hydrogen molecule the quadrupole nature of the CBOP energy-loss cross section leads to cross section values with impacting electron energy dependence and an angular behavior which are totally distinguishable from the usual ionization, inter-band transitions and dissociation processes. Previously established relationships between the CBOP and the polarizability of the overlap region suggest this an a promising theoretical tool for quantifying covalency in the chemical bond

Adaptive guided stochastic optimization: A novel approach for fitting the theoretical intensity parameters for lanthanide compounds

In this study, we introduce a state-of-the-art approach to enhance the fitting accuracy of theoretical intensity parameters in lanthanide spectroscopy. Lanthanide-based compounds play a pivotal role in a wide range of applications due to their distinctive photophysical characteristics. Theoretical understanding and computational descriptions are essential for advancing these applications. The Judd-Ofelt theory stands as a fundamental stone, offering insights into the luminescence exhibited by lanthanide compounds. Our methodology addresses the procedure of fitting charge factors (g in the Simple Overlap Model) and ligand effective polarizabilities (α′ in the Bond Overlap Model), quantities used for the determination of the intensity parameters (Ωλ). We propose Adaptive Guided Stochastic Optimization (AGSO), a method that employs randomized initial points within predefined bounds for each variable. By iteratively updating variable bounds based on population statistics, AGSO systematically minimizes the error function with respect to experimental data. Extensive tests were conducted comparing AGSO with the well-established simulated annealing (SA) method. Remarkably, AGSO consistently outperformed SA, demonstrating its efficacy in fitting intensity parameters for various lanthanide compounds. Through AGSO, we offer a robust and efficient tool for the accurate study of lanthanide-based compounds, with broad implications for diverse applications

Synthesis and Characterization of the Europium(III) Pentakis(picrate) Complexes with Imidazolium Countercations: Structural and Photoluminescence Study

Six new lanthanide complexes of stoichiometric formula (C)(2)[Ln(Pic)(5)]-where (C) is a imidazolium cation coming from the ionic liquids 1-butyl-3-methylimidazolium picrate (BMIm-Pic), 1-butyl-3-ethylimidazolium picrate (BEIm-Pic), and 1,3-dibutylimidazolium picrate (BBIm-Pic), and Ln is Eu(III) or Gd(III) ions-have been prepared and characterized. To the best of our knowledge, these are the first cases of Ln(III) pentakis(picrate) complexes. The crystal structures of (BEIm)(2)[Eu(Pic)(5)] and (BBIm)(2)[Eu(Pic)(5)] compounds were determined by single-crystal X-ray diffraction. The [Eu(Pic)(5)](2-) polyhedra have nine oxygen atoms coordinated to the Eu(III) ion, four oxygen atoms from bidentate picrate, and one oxygen atom from monodentate picrate. The structures of the Eu complexes were also calculated using the sparkle model for lanthanide complexes, allowing an analysis of intramolecular energy transfer processes in the coordination compounds. The photoluminescence properties of the Eu(III) complexes were then studied experimentally and theoretically, leading to a rationalization of their emission quantum yields