Chemical Physics Letters最新文献

BaCe_0.8Sm_0.2-xNd_xO_3-δ (x = 0, 0.05, 0.1, 0.15) powder was prepared using the glycine-nitrate combustion method, its crystal structure, microscopic morphology and electrochemical properties were investigated. X-ray diffraction analysis showed that the BaCe_0.8Sm_0.2-xNd_xO_3-δ powder with orthorhombic perovskite structure could be obtained after calcined at 1150 °C. Scanning electron microscopy showed that BaCe_0.8Sm_0.2-xNd_xO_3-δ sintered samples exhibited a dense structure. Electrochemical impedance tests showed that the substitution of Nd³⁺ improved the electrical conductivity of the BaCeO₃-based electrolyte materials. The proton conductivity of BaCe_0.8Sm_0.15Nd_0.05O_3-δ samples reaches a maximum value of 0.035 S cm⁻¹ in a wet air environment at 700 °C.

The dielectric and infrared vibrational properties of single crystal Al₃BC₃ were computed using density functional perturbation theory. Utilizing a group theory approach, the frequencies and vibrational modes of all the infrared active modes at the Brillouin zone center were determined. The study explored the dielectric function, infrared reflectivity, and Born effective charge of Al₃BC₃ in directions both parallel and perpendicular to the c-axis. The analysis of the Born effective charge confirmed the existence of strong covalent bonds between B and C, as well as ionic bonds between Al and C in Al₃BC₃ ceramics.

Polycyclic aromatic hydrocarbons (PAH) molecules serve as fundamental building blocks in the formation of graphene, a highly versatile material with diverse applications. Understanding the electrical properties of PAH molecules is pivotal in defining the conductivity of graphene, as the latter’s conductive behavior is inherently linked to its molecular structure. Electron affinity (EA) stands out as a crucial parameter in assessing the electrical characteristics of PAH molecules. However, the experimental determination of EA entails significant costs, prompting researchers to turn to computational methods for estimation. Despite advancements in computational resources and theoretical techniques, particularly within density functional theory (DFT), the optimal method for estimating EA remains unclear. In this study, we systematically evaluate various functionals and basis sets to determine the most accurate approach for estimating the electron affinity of PAH molecules.

Slow solvation dynamics and abundant non-bonding interactions in polymer matrix can modulate photophysical properties of guest chromophores. In this work, we used fisetin as a fluorescent probe to explore the microenvironment in poly vinyl alcohol (PVA) matrix and its effect on excited-state proton transfer (ESPT). Compared to in PVA solution, fluorescence of fisetin in PVA film is largely enhanced and ESPT barrier is increased. Both bulk polarity of PVA film and site-specific intermolecular hydrogen bonding between water and fisetin were determined to contribute to anomalous absorption and emission properties absent in solutions.

High-quality data-driven potentials were developed aiming to predict rovibrational traits and analyze the influence of the isotopic substitution on the molecular spectroscopic properties of Ar${}_2$H${}^{+}$. Neural networks machine-learning approaches trained on CCSD(T)/CBS datasets were implemented. Our full-dimensional quantum MCTDH results were discussed in comparison with experimental data in gas phase and solid matrix environments, as well as against theoretical estimates available. The new data indicate that both fundamental and progression bands are dominantly driven by the strength and shape of the underlying interactions. Our simulations could enable the spectroscopic characterization of these species, assisting investigations for their astrophysical observation.

The effect of a static electric field ionization on the neutral hydrogen molecule H₂ confined in a spherical potential well is studied, as a simple model for the chemical activation of molecular species in a medium. Quantum diffusion Monte Carlo is employed with complete account of electron correlation. Field-induced ionization and dissociation are discussed, for different values of the confinement radius and electric field strength. This study allows to highlight the mechanism of electric field initiation of chemical reactions in fluids at different pressures, without the details of a specific chemical environment.