134 research outputs found
4-(5-Amino-1H-1,2,4-triazol-3-yl)pyridinium chloride monohydrate
In the cation of the title compound, C7H8N5
+·Cl−·H2O, the mean planes of the pyridine and 1,2,4-triazole rings form a dihedral angle of 2.3 (1)°. The N atom of the amino group adopts a trigonal–pyramidal configuration. The N atom of the pyridine ring is protonated, forming a chloride salt. In the crystal, intermolecular N—H⋯O, N—H⋯N, N—H⋯Cl and O—H⋯Cl hydrogen bonds link the cations, anions and water molecules into layers parallel to the (1, 0, ) plane
Confinement and correlation effects in the Xe@C60 generalized oscillator strengths
The impact of both confinement and electron correlation on generalized
oscillator strengths (GOS's) of endohedral atoms, A@C60, is theoretically
studied choosing the Xe@C60 4d, 5s, and 5p fast electron impact ionization as
the case study. Calculations are performed in the transferred to the atom
energy region beyond the 4d threshold, omega = 75--175 eV. The calculation
methodology combines the plane wave Born approximation, Hartree-Fock
approximation, and random phase approximation with exchange in the presence of
the C60 confinement. The confinement is modeled by a spherical
delta-function-like potential as well as by a square well potential to evaluate
the effect of the finite thickness of the C60 cage on the Xe@C60 GOS's.
Dramatic distortion of the 4d, 5p, and 5s GOS's by the confinement is
demonstrated, compared to the free atom. Considerable contributions of
multipolar transitions beyond dipole transitions in the calculated GOS's is
revealed, in some instances. The vitality of accounting for electron
correlation in calculation of the Xe@C60 5s and 5p GOS's is shown.Comment: 7 pages, 3 figures, submitted to Physical Review
Diffuse versus square-well confining potentials in modelling @C atoms
Attention: this version- of the manuscript differs from its previously
uploaded version- (arXiv:1112.6158v1) and subsequently published in 2012 J.
Phys. B \textbf{45} 105102 only by a removed typo in Eq.(2) of version-;
there was the erroneous factor "2" in both terms in the right-hand-side of the
Eq.(2) of version-. Now that the typo is removed, Eq.(2) is correct.
A perceived advantage for the replacement of a discontinuous square-well
pseudo-potential, which is often used by various researchers as an
approximation to the actual C cage potential in calculations of
endohedral atoms @C, by a more realistic diffuse potential is
explored. The photoionization of endohedral H@C and Xe@C is
chosen as the case study. The diffuse potential is modelled by a combination of
two Woods-Saxon potentials. It is demonstrated that photoionization spectra of
@C atoms are largely insensitive to the degree of diffuseness
of the potential borders, in a reasonably broad range of 's.
Alternatively, these spectra are found to be insensitive to discontinuity of
the square-well potential either. Both potentials result in practically
identical calculated spectra. New numerical values for the set of square-well
parameters, which lead to a better agreement between experimental and
theoretical data for @C spectra, are recommended for future studies.Comment: 11 pages, 4 figure
Correlation structure in nondipole photoionization
The nondipole parameters that characterize the angular disribution of the
photoelectrons from the 3d subshell of Cs are found to be altered qualitatively
by the inclusion of correlation in the form of interchannel coupling between
the and photoionization channels. A prominent
characteristic maximum is predicted only in the parameters for
photoionization, while the effect for is rather weak. The results
are obtained within the framework of the Generalized Random Phase Approximation
with Exchange (GRPAE), which in addition to the RPAE effects takes into account
the rearrangement of all atomic electrons due to the creation of a 3d vacancy
NbS: A unique quasi one-dimensional conductor with three charge density wave transitions
Through transport, compositional and structural studies, we review the
features of the charge-density wave (CDW) conductor of NbS (phase II). We
highlight three central results: 1) In addition to the previously reported CDW
transitions at = 360\,K and = 150\,K, another CDW transition
occurs at a much higher temperature = 620-650\,K; evidence for the
non-linear conductivity of this CDW is presented. 2) We show that CDW
associated with the - transition arises from S vacancies acting as
donors. Such a CDW transition has not been observed before. 3) We show
exceptional coherence of the -CDW at room-temperature. Additionally, we
report on the effects of uniaxial strain on the CDW transition temperatures and
transport.Comment: 16 pages, 18 figure
E1-E2 Interference in the VUV Photoionization of He
We have measured the forward-backward asymmetry of photoelectron angular distributions produced in the vacuum ultraviolet photoionization of helium. This asymmetry, a consequence of the breakdown of the dipole approximation, measures the real part of the ratio of the quadrupole and dipole matrix elements. In the autoionization region, the strong energy dependence of the asymmetry permits an experimental separation of the ratio of those magnitudes from their phase difference. We experimentally determined the Fano parameters of the 2p21D2 quadrupole resonance, and report improved values of the width Γ and line profile parameter q from those previously available from electron scattering. Off resonance, the smooth energy dependence of the asymmetry is found to agree well with the theoretical treatment presented here which incorporates higher multipole effects
Distortion and preservation of Giant resonances in Endohedral Atoms A@C60
It is demonstrated in this Letter that the effect of the fullerene shell upon
atomic Giant resonance decisively depends upon energy of photoelectrons, by
which the resonance decay. According to the prediction in [1], the Giant
resonance in Xe is strongly modified in the endohedral Xe@C60 being transformed
from a single broad and powerful maximum in Xe into four quite narrow but with
almost the same total oscillator strength. On the contrary, the 4d Giant
resonances in ions Ce3+ (the electronic structure that Ce has, when stuffed
into fullerene), in Ce4+, and Eu are considered. In none of them the 4d Giant
resonance in endohedrals is affected essentially. This is because the decay of
the Giant resonances in these endohedrals proceeds by emission of fast
photoelectrons that are almost unaffected by the C60 shell. The results
obtained give at least qualitative explanation to the fact that recent
observation of 4d Giant resonance in Ce@C82+, where the Giant resonance was
observed as a maximum without noticeable structure.Comment: 10 pages, 5 figure
ЗАВИСИМОСТЬ УСПЕШНОСТИ ПРОХОЖДЕНИЯ АЛЬФА-ТРЕНИНГА ОТ ЭКСТРАВЕРСИИ И НЕЙРОТИЗМА
The present paper shows the relationship of the success rate of alpha-training – learning to voluntarily increase the power of the alpha-rhythm with the help of the neurofeedback – with factors of the "Big Five" model of personality traits (NEO–FFI). It was found that most successful at the task of training were the subjects with low scores on Extraversion dimension and moderately high scores on Neuroticism dimension.Показана связь успешности прохождения альфа-тренинга – обучения произвольному увеличению мощности альфа-ритма при помощи технологии биоуправления – с факторами «большой пятерки» личностных черт (NEO-FFI). Установлено, что c задачей тренинга наиболее успешно справляются испытуемые с низкими баллами по шкале «Экстраверсия» и умеренно высокими баллами по шкале «Нейротизм»
Nb S3: A unique quasi-one-dimensional conductor with three charge density wave transitions
© 2017 American Physical Society.We review the features of the charge density wave (CDW) conductor NbS3 (phase II) and include several additional results from transport, compositional, and structural studies. Particularly, we highlight three central results: (1) In addition to the previously reported CDW transitions at TP1=360K and TP2=150K, a third CDW transition occurs at a much higher temperature TP0≈620-650K; evidence for the nonlinear conductivity of this CDW is presented. (2) We show that the CDW associated with the TP2 transition arises from S vacancies acting as donors. Such a CDW transition has not been observed before. (3) We demonstrate the exceptional coherence of the TP1 CDW at room temperature. The effects of uniaxial strain on the CDW transition temperature and transport are reported
European Red List of Habitats Part 1. Marine habitats
The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of categories and criteria, and detailed data and expert knowledge from involved countries1. A total of 257 benthic marine habitat types were assessed. In total, 19% (EU28) and 18% (EU28+) of the evaluated habitats were assessed as threatened in categories Critically Endangered, Endangered and Vulnerable. An additional 12% were Near Threatened in the EU28 and 11% in the EU28+. These figures are approximately doubled if Data Deficient habitats are excluded. The percentage of threatened habitat types differs across the regional seas. The highest proportion of threatened habitats in the EU28 was found in the Mediterranean Sea (32%), followed by the North-East Atlantic (23%), the Black Sea (13%) and then the Baltic Sea (8%). There was a similar pattern in the EU28+. The most frequently cited pressures and threats were similar across the four regional seas: pollution (eutrophication), biological resource use other than agriculture or forestry (mainly fishing but also aquaculture), natural system modifications (e.g. dredging and sea defence works), urbanisation and climate change. Even for habitats where the assessment outcome was Data Deficient, the Red List assessment process has resulted in the compilation of a substantial body of useful information to support the conservation of marine habitats
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