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We have measured119Sn Mössbauer spectra of the CePtSn and (Ce0.9La0.1)NiSn compounds in the range from 1.5 to 293 K. In CePtSn, the spectra observed above 8 K are well explained by an electric quadrupole interaction. The spectral shape changes below 8 K due to the presence of a magnetic hyperfine field produced by the ordering of the Ce magnetic moments. We have analyzed these spectra assuming an incommensurate magnetic structure. The temperature dependence of the magnetic hyperfine field matches with anS=1/2 mean field curve with a step at 5 K. In (Ce0.9La0.1)NiSn, no magnetic order exists down to 1.5 K. 相似文献
4.
Summary Polarized absorption, emission and excitation spectra of Cs2CdCl4∶Mn2+ and emission as well as excitation spectra of CsCaCl3∶Mn2+ single crystals at temperatures down to 77 K are reported. The general features of the spectra are fruitfully analysed within
the framework of the strong field scheme of Tanabe and Sugano including Trees' correction. Some finer structure of the crystal
field independent levels are observed which are rationalized in terms of vibrational mechanism. A detailed analysis of the
spectra indicates octahedral site symmetry around the central metal ion.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
5.
《Solid State Ionics》1986,20(1):9-15
Near-infrared and visible absorption spectra at room temperature of MnPS3, CoPS3, CoPS3 are reported. These materials show weak structures below their fundamental absorption thresholds, due to the 3d-3d transitions occurring on the transition metal ion. By comparison with other transition metal compounds, such excitations are interpreted on the basis of the ligand field theory. The appearance of well developed crystal field spectra is a further confirmation that these materials are considerably ionic. 相似文献
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The effects of electric field on excitons have been investigated experimentally by means of electroabsorption (EA). The behavior of excitons with ionization fields FI of the same order of magnitude as or smaller than typical applied fields is reported. EA spectra associated with excitons in TlBr, PbI2, BiI3, trigonal Se, and α-monoclinic Se will illustrate this case. In this situation the EA signal arises principally from the effect on the exciton ground state, and no finer structure could be detected. The exciton ground state undergoes a shift to higher energies with the applied field. Characteristic dependences with field of the sizes, energy position of the peaks, and zero crossing points of the EA signals have been found. Estimates of exciton parameters can be readily obtained from the EA spectra. Unusual features of the exciton EA spectra PbI2 are discussed. Qualitatively, at least, theoretical predictions are obeyed. 相似文献
7.
Laser excited S1→S0 fluorescence spectra are obtained from p-fluorotoluene in a supersonic jet in order to probe internal rotational-vibrational
coupling. Resolved fluorescence spectra after selective excitation of S1 levels with high quanta states of the CH3 internal rotation contain evidence of extensive interactions with isoenergetic vibrational levels. Analogous spectra from
states without excitation of the internal rotor show little or no interactions. The results are consistent with a recently
developed theory of the intramolecular collisional transfer of rotor energy to the vibrational field. 相似文献
8.
An analysis of the 4.2 K spectra of FexO (x∼0.91) and (Fe0.4Mg0.6)xO is presented in which it is considered that because of the large electric field gradient at Fe2+ defect sites, the spectra cannot be described by Lorentzian sextets. It is assumed that the magnetic hyperfine field vector
is oriented at random in the coordinate system defined by the EFG main axis, and that the EFG coordinate system is also distributed
randomly. The simplifying assumption of the asymmetry parameter η=0 allows an analytical formula to be used to describe the
complex spectra.
Distributions of both magnetic hyperfine field and quadrupole interaction were progressively refined resulting in reasonable
fits to the spectra with the main features being well reproduced. The magnetic hyperfine field distribution is rather broad
with several features present while distinct values were obtained in the distribution of quadrupole interactions. These latter
values are considered to correspond to the defect configurations around the Fe2+ sites. The distribution of hyperfine fields is considered to reflect the varying strengths of superexchange due to the high
defect concentration as well as the effects of magnetic relaxation. 相似文献
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The nonequilibrium surface of single-crystal lanthanum hexaboride needles and its modifications are studied with a time-of-flight atomic probe. The surface is obtained by room-temperature field evaporation. The mass spectra of field evaporation shed light on the surface composition at the needle tip immediately after tip etching, corrosion in residual gases, intense cleaning by field evaporation, and the relaxation of the nonequilibrium surface by heating to 1250 K. Conditions for the breakdown of an oxide film on the tip surface and for obtaining the mass spectra of field evaporation for stoichiometric or lanthanum-enriched pure LaB6 single crystals are discussed. 相似文献
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Amorphous Sc3Fe alloy has been prepared by splat-cooling with levitation melting. The quadrupole splitting distributions for Sc3Fe were determined from Mössbauer spectra: the zero-field distribution has a Gaussian form. The analysis of Mössbauer spectra taken in applied magnetic field show that both positive and negative signs of principal component (Vz2) of electrical field gradients (EFG) are present. The crystallization process has also been investigated. Heat treatment of the amorphous alloys causes crystallization first into a metastable, and then into the stable phase. 相似文献
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Mössbauer spectra of the spinel series Ca
x
Co1–x
Fe2O4, withx=0.0, 0.05 and 0.10, have been collected between 80 and 300 K and in an applied field of 6 T at 4.2 K. From the shape-independent hyperfine field distribution fits of the external field spectra, and from the binomial distribution fits of the temperature-dependent spectra, the hyperfine field and the center shift could be unambiguously assigned to octahedrally and tetrahedrally coordinated ferric ions. The importance of the application of an external field in conjunction with a reasonable physical model to obtain a correct assignment of hyperfine parameters to a specific site is demonstrated. 相似文献
13.
The band spectrum of cyclotron waves propagating in a periodic layered semiconductor-insulator structure at an angle to an
external magnetic field that is applied perpendicularly to the layers is calculated for two relationships between the characteristic
frequencies of the semiconductor: ωH>ωP and ωH<ωP. The wave field distributions across the layers and over the period of the structure are analyzed. In both spectra, transmission
bands arise when the conditions for dimensional resonance across the semiconductor layer are fulfilled. The graphic solution
of the dispersion relation demonstrates that the cyclotron wave spectrum can be subdivided into two spectra of normal waves
according to the Bloch wavenumbers of the periodic structure. The cases where the band spectra complement each other or overlap
are considered. 相似文献
14.
E. K. Sadykov A. A. Yurichuk V. Yu. Lyubimov G. I. Petrov 《Hyperfine Interactions》2006,167(1-3):897-901
The theory of formation of the RF Mössbauer spectra for the “easy”-plane type magnetics (FeBO3) and for various types of RF field polarization is presented. Experiments using both linearly and circularly polarized external RF fields were carried out at different temperatures. At room temperature the experimental spectra for both cases are well described by switching hyperfine (hf) field model. At temperatures close to the Neel temperature (335 K), the spectra in the oscillating and rotating RF field were obtained and their forms are described by models of switching and rotating hf field, respectively. 相似文献
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R.V. Vedrinskii L.A. Bugaev I.I. Gegusin V.L. Kraizman A.A. Novakovich S.A. Prosandeev R.E. Ruus A.A. Maiste M.A. Elango 《Solid State Communications》1982,44(10):1401-1407
The cluster calculations of K and L2,3 edge XANES of K and Cl in KCl within the multiple scattering theory formalism using nonlocal HF potentials with abd without consideration of core hole field were performed. For K spectra the influence of the core hole potential is rather weak and the results are similar to those obtained with Xα potentials. For L2,3 spectra, particularly for that of K+, core hole field leads to a radical redistribution of oscillator strength caused mainly by the spatial rearrangement of d like states. Calculated XANES curves show good over-all agreement with the experimental spectra (the L2,3 absorption of K+ in KCl was measured using the synchrotron radiation of the USSR Academy of Sciences storage ring VEPP-2M in Novosibirsk). 相似文献
16.
A. N. Romanov D. N. Vtyurina E. V. Haula D. P. Shashkin N. A. Pimkin M. S. Kuznetsov I. S. Lisitsky V. N. Korchak 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(5):735-739
Single-crystal samples of RbY2Cl7 ternary chloride containing an Bi+ isomorphic impurity are prepared for the first time. The optical absorption spectra in the visible region and photoluminescence spectra in the near-IR associated with the presence of Bi+ impurity center are studied. The kinetics of the photoluminescence decay is investigated. The influence of the symmetry of the crystal field on the arrangement of the energy levels and on the characteristics of the absorption and photoluminescence spectra of Bi+ is demonstrated. 相似文献
17.
The chemical states of119Sb5+ ions hydrolytically adsorbed on spinel type ferrimagnetic oxide CoFe2O4 powders are studied by means of emission Mössbauer spectroscopy of the daughter nuclide119Sn. The spectra show a broadening which is attributed to the supertransferred hyperfine magnetic field coming from the magnetically ordered metal ions of the substrate. Distribution of the field is obtained from the spectra and its change with temperature is discussed. 相似文献
18.
V. F. Agekyan N. A. Grunina A. Yu. Serov N. G. Filosofov G. Karczewski 《Physics of the Solid State》2014,56(11):2149-2154
The emission spectra of planar structures based on CdTe and Cd1 ? x Mg x Te containing periodically built-in MnTe layers with a nominal thickness of one monolayer have been investigated. The luminescence spectra and luminescence excitation spectra of manganese ions and excitons, as well as the dependences of the spectra on the temperature and magnetic field strength, are used to determine the actual distribution of manganese ions. The full width at half-maximum of the profile describing the change in the concentration of manganese in the growth direction of the structures is estimated to be 7–8 monolayers. 相似文献
19.
We report on the magnetic-field-dependent optically detected magnetic resonance (ODMR) spectra for polycrystalline samples
of the bridged Zr(IV) metallocenes, Me2Si<(Cp2)ZrCl2 ( (dimethylsilylbis(cyclopentadienyl)zirconium-dichloride) and Me2C<(Cp2)ZrCl2 (iso-propylidenebis(cyclopentadienyl)zirconium-dichloride). ODMR spectra at zero magnetic field were recorded by frequency
sweeping a microwave source from 0.1 to 10 GHz with the sample contained in a microwave helix. ODMR spectra at finite magnetic
fields were recorded with the sample contained in either a helix or a slotted-tube resonator with a fixed microwave frequency
and sweeping the magnetic field. For all experiments, the sample and microwave probes were contained in an immersion dewar
cryostat, and the temperature was held at about 2 K. All three zero field ODMR transitions (2|E|, and |D| − |E| and |D|+|E|) were observed in the frequency-swept ODMR spectra recorded at zero and small magnetic fields. The zero-field frequency-swept
spectra allowed the determination ofD andE values uniquely. For frequency-swept small-field ODMR spectra recorded at successively higher magnetic fields, each of the
ODMR line intensities was observed to increase with increasing magnetic field. This intensity increase was observed for all
three ODMR lines, reflecting an increase in the total intensity rather than simply a change in the polarization of the triplet
sublevels. The latter would result in a change in the relative intensities of the ODMR lines but would not change simultaneously
the intensities of all three lines. The ODMR line intensities increase in proportion toB
n, wheren<1. This field dependence is weaker than the expected proportionalB
2 dependence from the Zeeman effect, which likely originates from the magnetic field dependence of the spin relaxation rates
between the triplet sublevels. Magnetic-field-swept ODMR spectra recorded at fixed microwave frequencies in the X-band frequency
range (9.8 GHz) do not show all three expected classic Pake powder pattern line shape profiles, exhibited by the molecules
with their magneticZ, Y, andX axes parallel to the external magnetic field. In particular, the intensity for molecular magneticY-axes parallel to the external magnetic field is completely suppressed. In addition, an external magnetic field dependence
in field-swept ODMR spectra was observed, which results in a linear decrease of the ODMR intensity with increasing strength
of the external magnetic field over and above that would be expected in a polycrystalline spectrum. The data are analyzed
by simulation of the continuous-wave ESR spectrum with the eigenvalues and eigenvectors of the spin Hamiltonian matrix characterizing
the triplet state exhibiting the ODMR spectrum, in conjunction with homotopy, as a function of the orientations of the magnetic
axes of the various molecules in a polycrystalline sample. This approach is useful to interpret the experimentally observed
ODMR transition frequencies andg-values but does not take the amplitudes in the ODMR spectrum. The corrections required to modify the continuous-wave ESR
spectral amplitudes that reproduce the observed ODMR amplitudes are effects associated with the ODMR processes. 相似文献
20.
Results of the optical spectroscopy investigation of the cubic paramagnetic center Yb3+ ion in the Cs2NaYF6 single crystal are presented. The Stark level energies of the Yb3+ multiplets are established from absorption, luminescence and excitation luminescence spectra and the crystal field parameters are calculated. Information about the phonon spectra of Cs2NaYF6 crystals is obtained from the electron-vibrational structure of the optical absorption and luminescence spectra. 相似文献