123 research outputs found
Quantum Hall Effect induced by electron-electron interaction in disordered GaAs layers with 3D spectrum
It is shown that the observed Quantum Hall Effect in epitaxial layers of
heavily doped n-type GaAs with thickness (50-140 nm) larger the mean free path
of the conduction electrons (15-30 nm) and, therefore, with a three-dimensional
single-particle spectrum is induced by the electron-electron interaction. The
Hall resistance R_xy of the thinnest sample reveals a wide plateau at small
activation energy E_a=0.4 K found in the temperature dependence of the
transverse resistance R_xx. The different minima in the transverse conductance
G_xx of the different samples show a universal temperature dependence
(logarithmic in a large range of rescaled temperatures T/T_0) which is
reminiscent of electron-electron-interaction effects in coherent diffusive
transport.Comment: 6 pages, 3 figures, 1 tabl
How minor structural changes generate major consequences in photophysical properties of RE coordination compounds; resonance effect, LMCT state
Lanthanide coordination compounds of the formula Na[Ln(L)4] (1Ln), where Ln ¼ La3þ, Eu3þ, Gd3þ, Tb3þ,
L ¼ [L] and HL ¼ dimethyl(4-methylphenylsulfonyl)amidophosphate, were synthesized. Their structural and
spectroscopic properties were discussed in detail based on X-ray diffraction measurements, IR spectroscopy,
absorption and emission spectroscopy at 293 and 77 K and theoretical calculations of the intramolecular
energy transfer (IET) rates. DFT calculations were used to investigate the 1Ln electronic properties required to
calculate the transition rates. 30 and 22 pathways of intramolecular nonradiative energy transfer were
examined in the case of 1Eu and 1Tb, respectively. It is shown that the main pathway for sensitization of the
lanthanide emission is either the triplet (1Eu) or singlet (1Tb) transfer, occurring mainly through the exchange
mechanism. The energy rates for energy transfer from S1 and T1 equal WS ¼ 1:53 105 s 1 (1Eu),
WT ¼ 5:14 106 s 1 (1Eu) and WS ¼ 4:09 107 s 1 (1Tb), WT ¼ 6:88 105 s 1 (1Tb). The crucial role of
the 7F5 level in the energy transfer process of 1Tb and the participation of the LMCTstate in the depopulation of
the ligand singlet state of 1Eu were demonstrated. The influence of the resonance effect on the splitting of the
7F1 level in 1Eu was analyzed. By comparing the properties of 1Ln with the properties of 2Ln coordination
compounds, sharing the same ligand and crystallizing in the same crystallographic system (monoclinic), but
with a different space group, it is demonstrated how slight structural changes can affect the photophysical
properties of Ln compounds.publishe
The Relativistic Linear Singular Oscillator
Exactly-solvable model of the linear singular oscillator in the relativistic
configurational space is considered. We have found wavefunctions and energy
spectrum for the model under study. It is shown that they have correct
non-relativistic limits.Comment: 14 pages, 12 figures in eps format, IOP style LaTeX file (revised
taking into account referees suggestions
Measurement of the cross section with the CMD-3 detector at the VEPP-2000 collider
The process has been studied in the
center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23
pb collected with the CMD-3 detector at the VEPP-2000 collider.
Using about 24000 selected events, the cross
section has been measured with a systematic uncertainty decreasing from 11.7\%
at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of
production dynamics has been performed
Study of the process in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector
Using a data sample of 6.8 pb collected with the CMD-3 detector at the
VEPP-2000 collider we select about 2700 events of the process and measure its cross section at 12 energy ponts with about
6\% systematic uncertainty. From the angular distribution of produced nucleons
we obtain the ratio
Electroproduction, photoproduction, and inverse electroproduction of pions in the first resonance region
Methods are set forth for determining the hadron electromagnetic structure in
the sub--threshold timelike region of the virtual-photon ``mass'' and
for investigating the nucleon weak structure in the spacelike region from
experimental data on the process at low energies. These
methods are formulated using the unified description of photoproduction,
electroproduction, and inverse electroproduction of pions in the first
resonance region in the framework of the dispersion-relation model and on the
basis of the model-independent properties of inverse electroproduction.
Applications of these methods are also shown.Comment: The revised published version; Revtex4, 18 pages, 6 figure
Density Matrix Kinetic Equation Describing a Passage of Fast Atomic Systems Through Matter
The quantum-mechanical consideration of a passage of fast dimesoatoms through
matter is given. A set of quantum-kinetic equations for the density matrix
elements describing their internal state evolution is derived. It is shown that
probabilistic description of internal dynamics of hydrogen-like atoms is
impossible even at sufficiently low energies because of the ``accidental''
degeneracy of their energy levels.Comment: 12 pages, LATEX, submitted to J. Phys.
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