Research and modeling of laser ablation by ultra-short laser pulses for metal targets

In this article an improved mathematical model for a laser metal ablation by ultra-short duration laser pulses is proposed. The model is based on two-temperature hydrodynamic model for electrons and ions and wide-range equation of state for metals. The results of the computer simulation for aluminum and copper are compared with experimental data at a different laser fluence and duration of pulses for ablation depth. A good agreement with them and the experimental data of ablation depth is received

Lattice dynamics and mixing of polar phonons in the rare-earth orthoferrite TbFeO3

Rare-earth orthoferrites are a promising platform for antiferromagnetic spintronics with a rich variety of terahertz spin and lattice dynamics phenomena. For instance, it has been experimentally demonstrated that the light-driven optical phonons can coherently manipulate macroscopic magnetic states via nonlinear magnetophononic effects. Here using TbFeO3 as an example, we reveal the origin of the mode mixing between the LO and TO phonons, which is important for understanding of nonlinear phononics. We performed a comprehensive study of the lattice dynamics of the TbFeO3 single crystal by polarized infrared and Raman scattering spectroscopic techniques, and experimentally obtained and carefully analyzed the spectra of anisotropic complex dielectric functions in the far-infrared spectral range. This allowed us to reliably identify the symmetries and parameters of most infrared- and Raman-active phonons. Next, the experimental studies were supplemented by the lattice dynamics calculations which allowed us to propose the normal mode assignments. We reveal that the relation between LO and TO polar phonons is complex and does not strictly follow the “LO-TO rule” due to the strong mode mixing. We further analyze how displacements of different ions contribute to phonon modes and reveal that magnetic Fe ions are not involved in Raman-active phonons, thus shedding light on a lack of spin phonon coupling for such phonons. The obtained results establish a solid basis for further in-depth experimental research in the field of nonlinear phononics and magnetophononics in rare-earth orthoferrites

EARLY TRIASSIC CONCHOSTRACANS from the TIRYAKHKOBYUME SECTION (SOUTHERN VERKHOYANSK REGION, REPUBLIC of SAKHA (YAKUTIA))

© 2020 Kazan Federal University. All rights reserved. Conchostracans (Crustacea) from the Induan deposits of the Tiryakh-Kobyume section (southern Verkhoyansk region) were studied. We identified the following seven conchostracan species belonging to five genera: Pseudestheria Raymond, 1946; Euestheria Deperet et Mezeran, 1912; Sphaerestheria Novojilov, 1954; Lioestheria Deperet et Mezeran, 1912; Wetlugites Novojilov, 1958. Most of the previously identified species in the Tiryakh-Kobyume region (“Pseudestheria sibirica”, “Ps. tumaryana”, “Ps. kashirtzevi”, and “Sphaerestheria aldanensis”) were described in the middle of the 20th century from the basal Triassic in the western Verkhoyansk region (Balbuk section). Revision of these species with the use of modern methods of conchostracan classification is needed

Effect of the solvent nature and the number of electrophilic substituents in the molecule on hydration of nitro derivatives of phenanthrene-9,10-quinone

Solvates (1 : 2) of 10,10-dihydroxy-2,4,7-trinitro-9,10-dihydrophenanthren-9-one with DMSO and of 10,10-dihydroxy-2,7-dinitro-9,10-dihydrophenanthren-9-one with HMPA were prepared. The crystal structure of 2,5-dinitrophenanthrene-9,10-quinone was established. The results of X-ray diffraction analysis and IR spectroscopy of a series of mono-, di-, and trinitro derivatives of phenanthrene-9,10-quinone demonstrated that the ability of carbonyl groups to participate in nucleophilic addition of water increases as the number of nitro groups in substituted phenanthrene-9,10-quinone increases. The nature of the solvent (HMPA, DMF, or DMSO) affects hydration of phenanthrenequinones primarily due to the difference in the strength of intermolecular hydrogen bonds stabilizing di- and tetrahydroxydihydrophenanthrenes

Mechanism of defect formation in heavily Y-doped n-ZrNiSn. I. Crystal and electronic structures

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Synthesis, crystal structure, and spectroscopic studies of 10-(1-phthalazinylazo)-9-phenanthrol (HL). Complexation of cadmium and zinc chlorides with HL

10-(1-Phthalazinylazo)-9-phenanthrol (HL, I) was synthesized by the reaction between 1-hydrazinophthalazine and 9,10-phenanthrenequinone. The crystal and molecular structures of compound I were determined by X-ray diffraction (XRD). According to XRD, EAS, and 1H and 13C NMR data, a HL molecule in solutions and in crystals exists in the form of quinohydrazone tautomer (b) (s-trans, cis) stabilized by intramolecular N(3)H.O(1) hydrogen bond. The "mobile" H atom is localized at the N(3) atom of the azo group. The phthalazine (A) and phenanthrenequinone (B) moieties of the HL molecule are nearly coplanar. The HL basicity and acidity constants (pKa = 1.90 and pKa = 11.65, respectively) and the formation constants of HL complexes with Zn2+ and Cd2+ and their compositions in solutions were determined. ML2 · DMFA complexes, where M = Zn2+, Cd2+, were synthesized. The coordination mode of the L- ligand with metal atoms was suggested. © 2013 Pleiades Publishing, Ltd

Synthesis and structure of complexes of some d metals with 10-(2-benzothiazolylazo)-9-phenanthrole (HL). Crystal and molecular structures of [CdL2] · DMF

The coordination compounds of cadmium(II), zinc(II), nickel(II), cobalt(II), and copper(II) with 10-(2-benzothiazolylazo)-9-phenanthrole (HL) were isolated in the crystalline state and studied. The crystal structure of the cadmium complex [CdL2] · DMF was determined by X-ray diffraction. The ligand is attached to cadmium in the form of anion functioning as an O,N,N-tridentate chelating ligand; this is accompanied by a change in its isomer form. The Cd configuration is a distorted octahedron. © 2013 Pleiades Publishing, Ltd

First findings of Otoceras (Ceratitida) in the Kobyuma zone of the Southern Verkhoyansk region, Northeastern Russia

The samples of the genus Otoceras, which is an important biostratigraphic marker of the Permian-Triassic boundary deposits of the Boreal realm, were found in the Kobyuma structural and facies zone of the Southern Verkhoyansk region. The features of the geographic and vertical distribution of Otoceras in the northern part of the Southern Verkhoyansk region were considered. The age of Otoceras beds was discussed. In the Verkhoyansk region, the Otoceras beds are divided into Concavum and Boreale zones. In the Tiryakh-Kobyume section of the Kobyuma zone, two close levels with ceratites of the genus Otoceras were revealed. From the first (lower) level, Otoceras aff. gracile Tozer and O. sp. were identified, presumably related to the Concavum zone of the highest part of the Changhsingian stage (Permian, Lopingian Series). At the second (upper) level, a large specimen of the species Otoceras boreale Spath was discovered, which makes it possible to attribute the host deposits to the Boreale zone of the Induan stage base (Lower Triassic). A section interval containing ceratites of the genus Tompophiceras of the Pascoei and Morpheos zones was revealed above the Otoceras beds. Since no own Triassic local stratigraphic scheme has been established in the Kobyuma zone, it is expedient to use the Nekuchan Formation (Induan deposits) of the Allakh-Yun’ zone of the Southern Verkhoyansk region