A series of 12 asphaltene samples extracted from heavy oils and the oxidized bitumen different origin has been studied with high-frequency W-band (94 GHz) pulsed electron paramagnetic resonance (EPR) spectroscopy. Transverse (T2e) longitudinal (T1e) relaxation times free radical (FR) vanadyl porphyrin (VO2+) were measured for each sample. significant contribution spectral diffusion to T2e revealed ascribed dipole–dipole interaction between FR VO2+. This indicates that distance VO2+ does not...

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for development solid-state quantum technologies. Recently, one such defect has been found hexagonal boron nitride (hBN) and identified as a negatively charged vacancy (VB−). To explore utilize properties this defect, needs to design robust way its creation an hBN crystal. We investigate possibility creating VB− centers single crystal by means irradiation with high-energy (E = 2 MeV) electron flux....

Structural characterization of metalloporphyrins in complex systems such as native hydrocarbons is the focus scientific and industrial interests since many years. We describe electron-nuclear double resonance (ENDOR) crude oil from well without any additional sample treatment (i.e., environment) magnetic field about 3.4 T temperature 50 K by applying microwave pulses at 94 GHz (W-band) radiofrequency near proton Larmor frequencies 144 MHz to probe paramagnetic vanadyls. By means density...

The research focuses on the explanation of a phenomenon observed in spectra electron nuclear resonance (ENDOR) pertaining to nitrogen atoms adjacent boron vacancy (VB) defect hexagonal nitride (hBN). is manifested as shift ENDOR spectrum lines with respect Larmor frequency. It hypothesized that these shifts are indicative substantial hyperfine interaction between VB and 14N nuclei hBN. A calculation utilizing second-order perturbation theory was executed determine positions lines, resulting...

The concept of optically addressable spin states deep-level defects in wide band gap materials is successfully applied for the development quantum technologies. Recently discovered negatively charged boron vacancy (VB–) hexagonal nitride (hBN) potentially allow a transfer this onto atomic-thin layers due to van der Waals nature defect host. Here, we experimentally explore all terms VB– Hamiltonian reflecting interactions with three nearest nitrogen atoms by means conventional electron...

Vanadyl porphyrin complexes in asphaltenes from heavy (Karmalinskoye) oil and asphaltene films obtained as a result of adsorption on the surface aluminum oxide were studied by electron paramagnetic resonance (EPR) double electron-nuclear (ENDOR) W-band frequency range (microwave 95 GHz, magnetic field 3.4 T). Mims ENDOR spectra 1 H 27 Al nuclei are observed. different for native one side adsorbed samples other while no significant changes X- 9 GHz) or EPR found. The results allow supposing...

Optically active point defects in semiconductors have received great attention the field of solid-state quantum technologies. Hexagonal boron nitride, with an ultra-wide band gapEg= 6 eV, containing a negatively charged vacancy (VB-) unique spin, optical, and coherent properties presents new two-dimensional platform for implementation This work establishes value ofVB-spin polarization under optical pumping

The formation of the photopolaronic excitons in ABO${}_{3}$ perovskite-type oxides has been detected experimentally by means photoinduced electron paramagnetic resonance (EPR) studies KTa${}_{0.988}$Nb${}_{0.012}$O${}_{3}$ crystals. corresponding microwave x-band spectrum at $T<$ 10 K consists a narrow, nearly isotropic signal located $g$ \ensuremath{\sim} 2 and strongly anisotropic component. first signal, which rich structure due to hyperfine interactions with lattice nuclei, is attributed...

We report the observation of pulsed electron-nuclear double resonance (ENDOR) spectrum caused by interactions nitrogen nuclei 14N with unpaired electron paramagnetic vanadyl complexes VO2+ porphyrins in natural crude oil. provide detailed experimental and theoretical characterization hyperfine quadrupole tensors.

An effective approach to the improvement of biochemical status yeast cells before their immobilization was applied develop a biocatalyst with high level cell metabolic activity and viability that could be used for sparkling wine production. According approach, wine-containing medium (pH 3.0) routinely accumulation champagne biomass under aerobic conditions replaced by semi-synthetic one 5.6), usually growth. The variation temperature pH growth showed modification fatty acid pool yeasts its...

NV– defects in silicon carbide (SiC) are emerging as a competitive alternative to centers diamond due advanced industrial-scale SiC production methods. We present study of the ground-state electron–nuclear coupling negatively charged nitrogen-vacancy 6H-SiC crystal by electron paramagnetic resonance and double techniques. The hyperfine nuclear quadrupole interaction tensors have been precisely determined. is found be predominantly characterized an isotropic contact Fermi part aiso =...

Strongly anisotropic photoinduced electron paramagnetic resonance spectrum was found in the KTa1-x Nb x O3 crystals with = 0.012 at T < 10 K, which is described well within model of center S 1, g ∥ 0.82 ± 0.04, ⊥ 0.52 and D 0.44 0.03 cm−1. Analysis shows that this originates from Nb4+−O− polaronic exciton triplet state.

Abstract Structural characterization of asphaltenes in complex systems such as native hydrocarbons is the focus scientific and industrial interests since many years. Various analytical tools approaches are used for that. We present results our study asphaltene fractions A1 A2 with predominantly “island” type “archipelago” molecules by conventional pulsed electron paramagnetic resonance (EPR) at X-band (9 GHz) W-band (95 aim to expand abilities EPR technique characterization. Shift higher...

Observation of an intense optical linear dichroism arising in cubic KZnF3:Cr crystal at low temperatures under uniaxial stress applied along the four-fold axis is reported. Dichroism occurs range wide vibronic absorption band corresponding to 5Eg → 5T2g transition Cr2+ ions. Strain dependences value were studied 2.0 K, 4.2 and 77 K. We associate our observations with Jahn-Teller effect ground state ion. The model proposed based on a redistribution centers between minima E⨂e problem adiabatic...

Electron paramagnetic resonance studies of the impurity Fe$^{3+}$ and Mn$^{4+}$ centers indicate that symmetry crystal structure millimeter-scale strontium titanate plates above 105 K lowers in bulk from cubic to tetragonal, different conventional low-temperature antiferrodistortive phase. It is shown effect does not originate residual stress; its magnitude (observed tetragonal distortion) particular manifestations depend on plate orientation, surface quality geometry a sample. Peculiarities...