Ab Initio Study of the Influence of Spin and Orbital Magnetic Moments on the Stability of Magnetic and Charge Distribution in Co:ZnO Monolayer.

The development of ultrathin magnets with tunable magnetic properties is essential for advancing quantum computing technologies. In this study, density functional theory (DFT) calculations were employed to investigate the atomic and electronic structures of a ZnO monolayer embedded with cobalt atoms. The impact of spin dynamics on charge transfer within the Co:ZnO system was thoroughly examined.

Photoprocesses in Bis-Diethylamino Derivatives of 1,4- and 1,3-Distyrylbenzene.

The photoprocesses of diethylamino derivatives of 1,4- and 1,3-distyrylbenzenes in MeCN were studied using absorption, luminescence, H NMR, and laser kinetic spectroscopy. Compounds and undergo intersystem crossing to the triplet state and exhibit delayed fluorescence. It was concluded that dye radical anions and radical cations are formed upon dismutation of the triplet state in the presence of an electron donor or acceptor.

Possibilities of Controlling the Quantum States of Hole Qubits in an Ultrathin Germanium Layer Using a Magnetic Substrate: Results from ab Initio Calculations.

Using density functional theory in the noncollinear approximation, the behavior of quantum states of hole qubits in a Ge/Co:ZnO system was studied in this work. A detailed analysis of the electronic structure and the distribution of total charge density and hole states was carried out. It was shown that in the presence of holes, the energetically more favorable quantum state is the state |0˃, in contrast to the state |1˃ when there is no hole in the system.

Photoprocesses in Derivatives of 1,4- and 1,3-Diazadistyryldibenzenes.

Photoprocesses in 1,4-diazadistyrylbenzene () and 1,3-diazadistyrylbenzene derivative () diperchlorates in MeCN were studied by absorption, luminescence, and kinetic laser spectroscopies. For compound , -photoisomerization and intersystem crossing to a triplet state are observed. For compound , photoelectrocyclization is suggested.

DFT Analysis of Hole Qubits Spin State in Germanium Thin Layer.

Due to the presence of a strong spin-orbit interaction, hole qubits in germanium are increasingly being considered as candidates for quantum computing. These objects make it possible to create electrically controlled logic gates with the basic properties of scalability, a reasonable quantum error correction, and the necessary speed of operation. In this paper, using the methods of quantum-mechanical calculations and considering the non-collinear magnetic interactions, the quantum states of the system 2D structure of Ge in the presence of even and odd numbers of holes were investigated.

Quantum mechanical modelling of phosphorus qubits in silicene under constrained magnetization.

A non-collinear density functional theory calculation of the electronic and magnetic structure of phosphorus-doped silicene was performed using atomic constrained magnetization. The antiferromagnetic state for the local magnetic moments of a pair of phosphorus atoms was found to be preferable both without and with constrained magnetization. A spatial change in the charge densities in the regions of substituting phosphorus atoms was shown.

Analysis of Ionicity-Magnetism Competition in 2D-MX3 Halides towards a Low-Dimensional Materials Study Based on GPU-Enabled Computational Systems.

The acceleration of parallel high-throughput first-principle calculations in the context of 3D (three dimensional) periodic boundary conditions for low-dimensional systems, and particularly 2D materials, is an important issue for new material design. Where the scalability rapidly deflated due to the use of large void unit cells along with a significant number of atoms, which should mimic layered structures in the vacuum space. In this report, we explored the scalability and performance of the Quantum ESPRESSO package in the hybrid central processing unit - graphics processing unit (CPU-GPU) environment.

Ab Initio Prediction of Noncollinear Magnetic States of the Quantum Phosphorus Qubit in a Silicon Lattice.

The problem of the practical implementation of quantum computers is an important scientific and technological task at the present time. In this work, using first-principles calculations, a quantum qubit behavior based on a doped phosphorus atom in a Si lattice was theoretically investigated. The local magnetic field (), the local magnetization (), and the spin current density created by the excess electron from the phosphorus atom were calculated.

Pathways of electron transfer photosensitized by thiacyanine dimers.

Pathways of electron transfer reaction between p-nitroacetophenone (p-NAP) and ascorbic acid (AA) photosensitized by dimers of 3,3'-disulfopropyl-5,5'-dichlorothiacyanine triethylammonium (TC) and 3,3'-disulfopropyl-5,5'-dichloro-9,11-[ββ-dimethyltrimethylene]thiadicarbocyanine triethylammonium (TDC) are considered. In aqueous solution the dyes are present as an equilibrated mixture of monomers (M(-)) and dimers (M(2)(2-)). In contrast to monomers, the dimers of TC are characterized by a noticeable yield of intersystem crossing, whereas for TDC the triplet-triplet absorption of both monomers and dimers is easily observed upon ns-laser pulse.

Cyanine-based J-aggregates as a chirality-sensing supramolecular system.

J-aggregates are formed for 3,3'-disulfopropyl-5,5'-dichlorothiacyanine (Tc) and 3,3'-disulfobutyl-5,5'-diphenyl-9-ethyloxacarbocyanine (Oc) in aqueous solution in the presence of NaCl, Mg(NO(3))(2), d/l-tartaric acids, asparagine, proline, DNA, and proteins, such as lysozyme, trypsin, RNase, and gelatin. J-aggregates, which are formed in the presence of chiral additives, are optically active and characterized by sigmoidal kinetics with half-times of 10-1000 s, resonance fluorescence, and large CD amplitudes being up to 2° for Tc. Generally, the induced CD signals of the J-aggregates of both dyes are bisignate and the sign corresponds to that of the additive.

Kinetics of spontaneous formation of chiral J-aggregate of N-sulfobutyl oxacarbocyanine.

An oxacarbocyanine with N-sulfobutyl substituents, dye 1, exhibits an ability to form optically active J-aggregates in aqueous solution in the absence of chiral auxiliaries or templates. Optically active J-aggregates are formed in the absence (self-association) and presence of mono- and divalent metal ions. The time course of formation of J-aggregates is described by a sigmoidal time dependence and further characterized by an induction period.

J-aggregation of anionic ethyl meso-thiacarbocyanine dyes induced by binding to proteins.

The effects of ribonuclease A (RNase), lysozyme, trypsin, and bovine serum albumin (BSA) on the J-aggregation behavior of 3,3'-bis[sulfopropyl]-5-methoxy-4',5'-benzo-9-ethylthiacarbocyanine (1), 3,3'-bis[sulfopropyl]-4,5,4',5'-dibenzo-9-ethylthiacarbocyanine (2), and 3,3'-bis[sulfopropyl]-5,5'-dimethoxy-9-ethylthiacarbocyanine (3) were studied in aqueous solution. The formation of J-aggregates at pH 6 is induced by RNase for 1-3, by lysozyme for 1 and 2, and by trypsin for 2. The formation of J-aggregates correlates with decay of the dimers and is supported by induced circular dichroism spectra.

Kinetics of salt-induced J-aggregation of cyanine dyes.

The addition of monovalent, divalent, and trivalent metal ions to three anionic ethyl meso-thiacarbocyanine dyes, an ethyl meso-oxacarbocyanine, and an imidacarbocyanine in aqueous solution at room temperature results in the production of J-aggregates within the range of tens to hundreds of seconds. The rate of formation of J-aggregates correlates with the rate of decay of dimers or monomers and is dependent on the type of metal ion, dye structure, and temperature. The rate of formation of J-aggregates increases as the temperature decreases and the dye and salt concentrations increase, and the rate is highest for trivalent ions and smallest for monovalent ions, independent of the type of anion.

Kinetics of J-aggregation of cyanine dyes in the presence of gelatin.

The kinetics of formation of J-aggregates for 3,3'-bis[sulfopropyl]-R-4',5'-dibenzo-9-ethylthiacarbocyanines (R=5-methoxy; R=4,5-dibenzo) and 3,3'-bis[sulfopropyl]-5,5'-diphenyl-9-ethyloxacarbocyanine were studied in aqueous solution in the presence of gelatin at different pH values and at room and elevated temperatures. Addition of gelatin at concentrations of 0.0005-0.

Effect of macromolecules and Triton X-100 on the triplet of aggregated chlorophyll in aqueous solution.

Chlorophyll a (Chla) in aqueous solution (2-6% acetone) is present as mono- and dihydrated aggregated forms which are characterized by specific ground state absorption spectra. The amount of dihydrated form is larger in the presence of macromolecules, such as bovine serum albumin (BSA), lysozime and polyvinyl alcohol (PVA), increasing from BSA to lysozime and PVA. Chla in aqueous acetone with and without macromolecules is characterized by low fluorescence and the absence of triplet-triplet (T-T) absorption.

Fluorescence determination of trace amounts of uranium(VI) in various materials by a repetitive laser technique.

A laser-induced fluorescence method (LFM) is described for determination of trace amounts of uranium(VI), with a detection limit of 4 x 10(-11) g/ml. A repetitive pulsed laser, time discrimination and an averaging technique are used. The optimum time discrimination is obtained when the uranyl ion is complexed with phosphoric acid or sodium polysilicate.

[Electron transport in the chlorophyll aggregate oxidation reaction].

Flash photolysis study was carried out of electron transfer during rho-benzoquinone-photooxidation of monomeric and aggregated molecules of chlorophyll "a" in aqueous solutions of serum albumin and triton X-100. It has been found that in the presence of rho-benzoquinone oxidation of monomeres and aggregates of chlorophyll takes place; it results in the formation of the pigment cation-radicals. The kinetic analysis of the pattern of electron transfer during aggregates photooxidation enables a conclusion that oxidation proceeds only via the triplet state of the pigment molecules.

[Role of triplet exciplex in electron transport].

The role of triplet exciplex in electron transfer was considered in the photooxidation of chlorophylls "a" and "b" with p-benzoquinone and aromatic nitrous compounds. Relationship between the change of free energy delta F of formation of solvated ion-radical, ion-radical pairs and chlorophyll exciplex and dielectric constant of the medium & was investigated. The conclusions obtained were compared with the experimental data on the intermediate products.

[Study of electron transfer in pigment-protein complexes of photosystem I].

The electron transfer processes occuring in SDS chlorophyll--protein complexes of photosystem I were studied by flash photolysis. Transient species with lifetime about 5.10(-5) sec were found to be produced on flash excitation of complex buffer solutions.

[Nature of the electron excited state in pigment redox reactions. II. Analysis of the scheme of primary processes in the photooxidation reaction of chlorophylls a and b and pheophytin a ].

A scheme of primary reactions in photooxidation of pigments was considered assuming that electron transfer processes can occur via singlet excited as well as triplet states. The results of analysis are compared with the experimental data on relative yield values of chlorophylls a, b, and pheophytin a cation-radicals, as well as with the data on fluorescence quenching. A conclusion has been drawn that photooxidation of pigments proceeds exclusively via the triplet state.

[Nature of the electron-excited state in redox reactions of pigments. I. Photooxidation of chlorophyll a by n-benzoquine].

A method for studying the nature of electronic excited state under photooxidation is proposed. It is shown by an example of the oxidation of chlorophyll a with p-benzoquinone that the formation of cation-radicals of pigments proceeds only through the triplet state. On the basis of experimental data the values of the rate constants of formation of chlorophyll cation-radicals through the singlet-excited state (K2(1)--10(7) M-1 s-1) and triplet state (Kr=10(9) M-1 s-1) of the pigment are evaluated.

[Transient states in the photoreactions of chlorophyll-protein complexes].

Transient short-lived species arising in chlorophyll-protein complexes of PS I on flash excitation were studied by means of flash-photolysis and luminescence methods. Complexes were isolated from chloroplasts by the solubilisation in SDS and subsequent electrophoresis. Three different types of reactions associated with: a) the triplet state of monomeric chlorophyll; b) redox reactions in reaction centres; c) photochemical reactions of monomeric chlorophyll were established on excitation.

[Effect of the spectral composition of light on the mechanism of reaction of chlorophyll oxidation].

Photochemical oxidation of chlorophyll "a" on excitation of the pigment in different spectrum region (400-800 nm) was studied by flash photolysis. The absorption spectrum of chlorophyll cation-radical Chl+ was obtained and the values of extinction coefficient found. An attempt was made of photochemical generation of dication form of chlorophyll.

[Excited complexes in oxidation-reduction photoreactions of pigments. I. Spectral detection of triplet state exciplex in the chlorophyll oxidation reaction].

Photooxidation of chlorophyll "a" with p-benzoquinone in toluene and dioxane is studied by the method of flash photolysis. It is shown that in nonpolar medium the triplet exiplex is the product of this reaction. The experiments on competitive quenching of chlorophyll triplet state with naphthacene prove the diffusion mechanism of exiplex formation.