Electric polarizability of metallodielectric Janus particles in electrolyte solutions

Experiments and transport analysis describe the electric polarizability of JPs in a wide range of frequencies.

Strong spin–orbit interaction of photonic skyrmions at the general optical interface

Photonic skyrmions have applications in many areas, including the vectorial and chiral optics, optical manipulation, deep-subwavelength imaging and nanometrology. Much effort has been focused on the experimental characterization of photonic skyrmions. Here, we give an insight into the spin and orbital features of photonic skyrmions constructed by the p-polarized and s-polarized surface waves at an interface with various electric and magnetic properties by analyzing the continuity of chirality, energy flow and momentum densities through the electric and magnetic interface. The continuity of chirality density indicates that the photonic skyrmion has a property of the optical transverse spin. Most importantly, the continuity of energy flow and momentum densities results in four spin–orbit interaction quantities, which indicate the gradient of electric polarizability or permeability governs the spin–orbit interaction of photonic skyrmions and leads to the discontinuity and even the reversal of spin orientation through the optical interface. Our investigations on the spin–orbit properties of photonic skyrmions, which can give rise to the spin-dependent force and topological unidirectional transportation, is thorough and can be extended to other classical wave, such as acoustic and fluid waves. The findings help in understanding the spin–orbit feature of photonic topological texture and in constructing further optical manipulation, sensing, quantum and topological techniques.

Crystal structure, vibrational frequencies and polarizability distribution in hydrogen-bonded salts of pyromellitic acid

Structural features of moderate-to-strong O—H...O hydrogen bonds are related to the frequencies of O—H stretching vibrations and to the electric polarizability distribution in the donor and acceptor functional groups for crystals synthesized from the 1,2,4,5-benzenetetracarboxylic (pyromellitic) acid, namely: bis(3-aminopyridinium) dihydrogen pyromellitate tetrahydrate, (1); bis(3-carboxypyridinium) dihydrogen pyromellitate, (2); bis(3-carboxyphenylammonium) dihydrogen pyromellitate dihydrate, (3); and bis(4-carboxyphenylammonium) dihydrogen pyromellitate, (4). A combination of single-crystal X-ray diffraction, powder Raman spectroscopy and first-principle calculations in both crystalline and gaseous phases has shown that changes in the O—H...O hydrogen-bond geometry can be followed by changes in the corresponding spectral modes. Vibrational properties of moderate hydrogen bonds can be estimated from correlations based on statistical analysis of several compounds [Novak (1974). Struct. Bond. 18, 177–216]. However, frequencies related to very short O—H...O bonds can only be predicted by relationships built from a subset of structurally similar systems. Moreover, the way in which hydrogen bonds affect the polarizability of donor and acceptor groups depends on their strength. Moderate interactions enhance the polarizability and make it more anisotropic. Shorter hydrogen bonds may decrease the polarizability of a group as a consequence of the volume restraint implied by the neighbour molecule within a hydrogen-bonded aggregate. This is significant for evaluation of the electric susceptibility in crystals and, therefore, for estimation of refractive indices and birefringence.

Оптическая спектроскопия и сверхпроводимость купратов (О б з о р)

The optical properties of low-dimensional dielectric cuprates, including parent systems for high-temperature superconductors, such as La_2CuO_4, Sr_2CuO_2Cl_2, and YBa_2Cu_3O_6 are briefly reviewed. The main focus is on the d – d and p – d charge transfer transitions, which determine the fundamental absorption band. The analysis of optical properties shows the instability of parent cuprates against the d – d charge transfer with the formation of metastable electron–hole (EH) dimers of the Cu^1+–Cu^3+-type pairs coupled by the two-particle transfer and characterized by the giant electric polarizability. The formation of a system of stable EH dimers upon nonisovalent substitution determines the unconventional properties of the pseudogap and superconducting phases of doped cuprates.

Quantum Mechanical and Spectral Comparative Study of 1-p-Nitro-Benzoyl-Benzo[f]Quinolinium Methylid and 1-p-Nitrobenzoyl-2,3-Dicarbomethoxy-Pyrrolo-[1,2a]-Benzo[f]Quinoline

The quantum mechanical and spectral study of two related compounds, namely, 1-p-nitro-benzoyl-benzo[f]quinolinium methylid (BF1) and its cycloadduction derivative 1-p-nitro-benzoyl-2,3-dicarbomethoxy-pyrrolo-[1,2a]-benzo[f]quinoline (BF2) was carried out. Some electro-optical parameters in ground state were estimated by ab initio method. The solvatochromic behavior of the visible spectrum absorption band of the studied molecules in solvents with different macroscopic electro-optical proprieties was analyzed in order to estimate some microscopic molecular parameters of BF1 and BF2 in the excited state. Thus it was evidenced that, by excitation, the increase of BF1dipole moment and electric polarizability occurred while for BF2 either the increase or the decrease of these two parameters was found. The study is of practical importance for further synthesis of new derived compounds with potential applications in life sciences.