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1.
Haiyan Zhang Tingyu Liu Qiren Zhang Xi’en Wang Jigang Yin Min Song Xiaofeng Guo 《Journal of Physics and Chemistry of Solids》2008,69(7):1815-1819
The electronic structures of BaWO4 crystals containing F-type color centers are studied within the framework of the fully relativistic self-consistent Dirac-Slater theory, using a numerically discrete variational (DV-Xα) method. It is concluded that F and F+ color centers have donor energy level in the forbidden band. The optical transition energies are 2.449 and 3.101 eV, which correspond to the 507 and 400 nm absorption bands, respectively. It is predicted that 400-550 nm absorption bands originate from the F and F+ color centers in BaWO4 crystals. 相似文献
2.
D. Barba S. Jandl A.A. Martin C.T. Lin M. Cardona T. Wolf 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(3):277-281
Infrared reflectance, and transmission measurements as well as Raman scattering have been used to study the RE1+xBa2-xCu3O6 (RE = Nd, Sm) and YBa2Cu3O6 absorption bands in the 1100-1500 cm-1 infrared range as a function of temperature and beam polarization. In addition to two-phonon absorption between 1100 and
1170 cm-1, we observe excitations around 1400 cm-1, occurring in oxygen rich enclosures within the samples, and assign them to an excitation involving two-phonons plus the
270 cm-1 local mode related to Cu-O broken chains. Thus, the previously reported possible magnetic origin of the 1436 cm-1 sharp absorption band in YBa2Cu3O6 is contested.
Received 14 February 2001 and Received in final form 12 April 2001 相似文献
3.
Jigang Yin Qiren Zhang Tingyu Liu Xiaofeng guo Min Song Xien Wang Haiyan Zhang 《Current Applied Physics》2009,9(6):1237-1240
The electronic structures of SrMoO4 crystals containing F and F+ color centers with the lattice structure optimized are studied within the framework of the fully relativistic self-consistent Dirac–Slater theory, using a numerically discrete variational (DV-Xα) method. From the calculation, it is concluded that F and F+ color centers have donor energy level in the forbidden band. The electronic transition energies from the donor level to the bottom of the conduction band are 1.855 eV and 2.161 eV, respectively, which correspond to the 670 nm and 575 nm absorption bands. It is predicted that the 670 nm and 575 nm absorption bands originate from the F and F+ centers in SrMoO4 crystals. 相似文献
4.
运用相对论的密度泛函离散变分法(DV-Xα)研究了CaWO4晶体中F型色心的电子结构. 计算结果表明,F和F+心在禁带中引入了新的施主能级;分析了晶体内可能存在的光学跃迁模式,并通过过渡态的方法计算了F,F+心跃迁到导带底的能量分别为1.92eV和2.42eV. 因此,从理论上推断了F和F+心在CaWO4晶体中可能引起650nm和515nm的吸收,由此说明CaWO4晶体中650nm和515nm吸收带起源于晶体中的F和F+心.
关键词:
4晶体')" href="#">CaWO4晶体
+心')" href="#">F和F+心
DV-Xα 相似文献
5.
K.A. Schmidt M. Bergström G.B. Hagemann B. Herskind G. Sletten P.G. Varmette J. Domscheit H. Hübel S.W. Ødegård S. Frattini A. Bracco B. Million M.P. Carpenter R.V.F. Janssens T.L. Khoo T. Lauritsen C.J. Lister S. Siem I. Wiedenhöver D.J. Hartley L.L. Riedinger A. Maj W.C. Ma R. Terry 《The European Physical Journal A - Hadrons and Nuclei》2001,12(1):15-28
High-spin properties of the nucleus 169Hf have been studied through the fusion evaporation reaction 96Zr(76Ge,3n)169Hf at a beam energy of 310 MeV. The known rotational bands have been extended considerably and 6 new bands have been established,
four of which form coupled bands with pronounced M1 connections. Quasiparticle assignments are suggested for the new band structures, and it appears that coupling to vibrational
degrees of freedom plays a role. Both coupled bands involve the excitation of quasiprotons. In the region of highest spin,
a large alignment gain is interpreted in terms of a mixed crossing where an h
9/2 and an h
11/2 quasiproton provide the two signatures of the aligning configuration.
Received: 23 March 2001 / Accepted: 20 September 2001 相似文献
6.
P. Minutolo C. Corsi F. D'Amato M. De Rosa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):175-179
In this article we present experimental data for line parameters measurements of several transition lines of overtone bands
of C2H2 at 1540 nm. The measurements were done with a spectrometer based on a semiconductor diode laser and a direct absorption spectroscopy
scheme. Broadening and shift coefficients have been measured for the pure gas or in mixtures with N2, O2 and CO2 as perturbing gas.
Received 6 November 2000 and Received in final form 13 March 2001 相似文献
7.
Ts. Venkova M.-G. Porquet I. Deloncle B.J.P. Gall H. De Witte P. Petkov A. Bauchet T. Kutsarova E. Gueorgieva J. Duprat C. Gautherin F. Hoellinger R. Lucas A. Minkova N. Schulz H. Sergolle E.A. Stefanova A. Wilson 《The European Physical Journal A - Hadrons and Nuclei》1999,6(4):405-413
The 107,109Rh nuclei have been produced as fission fragments following the fusion reaction 28Si +176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. In both nuclei three new rotational bands with the odd
proton occupying the πg9/2, πp1/2 and π(g7/2/d5/2) sub-shells have been observed. In 107Rh, two other bands involving strong M1 transitions have been identified at excitation energy larger than 2 MeV. They can
be interpreted in terms of three quasiparticle excitations. In addition new structures consisting of four transitions, built
on states located at low excitation energy (680 keV in 107Rh and 642 keV in 109Rh), point out the importance of triaxial deformation in these two isotopes.
Received: 1 September 1999 相似文献
8.
A.V. Papoyan M. Auzinsh K. Bergmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):63-71
We report results of a theoretical and experimental study of the ground state nonlinear Hanle effect under strong laser excitation.
It is shown that besides the well-known zero-magnetic field suppression of absorption on F
g = F→F
e = F - 1 transitions caused by population trapping, an optical pumping induced enhanced absorption occurs on F
g = F→F
e = F + 1 transitions for small B-fields. The latter effect becomes more pronounced for high F values. The experiment with atomic vapor of Cs (D2 line, F
g = 4) confirms an increase of the spectrally unresolved fluorescence yield at zero magnetic field and 600 mW/cm2 laser intensity by 9% or 42%, when excitation occurs with linearly or circularly polarized light, respectively. The results
of the experiment agree with numerical simulation studies using equations of motion for a density matrix.
Received 24 November 2001 / Received in final form 25 March 2002 Published online 24 September 2002 相似文献
9.
C. Vadla V. Horvatic K. Niemax 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):23-25
The “forbidden” Pb 6p2
3P
0
↦6
p
2
3P1 line at 1278.9 nm is measured by diode laser absorption in a resistively heated hot-pipe filled with a lead vapour and argon
as buffer gas. The measurements performed at a temperature of 1170 K and a lead number density of 2.4×10
15
cm-3 yield the oscillator strength f
F
= (4.5±1.1)×10
-7
which corresponds to a radiative transition probability A
F
= (6.1±1.5) s-1. Within the error bars, the result is in agreement with theoretical data published by different authors.
Received 11 October 2000 and Received in final form 5 January 2001 相似文献
10.
Zhijun Yi Tingyu LiuQiren Zhang Yuanyuan Sun 《Journal of Electron Spectroscopy and Related Phenomena》2006
The electronic structures of PbWO4 crystals containing F type color centers with the lattice structure optimized are studied within the framework of the fully relativistic self-consistent Direc–Slater theory, using a numerically discrete variational (DV-Xα) method. The calculated results show that F and F+ centers have donor energy level in forbidden band. Their optical transition energy are 1.84 eV, 2.21 eV, respectively, which corresponds to the 680 nm, 550 nm absorption bands. It predicts that the 680 nm, 550 nm absorption bands originate form the F and F+ centers in PbWO4 crystals. 相似文献
11.
T. Mertelj D. Mihailovic 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(3):325-327
Photoinduced IR absorption measurements are reported on WO3. A photoinduced midinfrared small polaron peak centered at 4800 cm-1 (0.59 eV) was observed. The data were analyzed in the framework of the photon-assisted small-polaron hopping theory and briefly
compared to previously published infrared absorption measurements in WO3 and photoinduced IR absorption measurements in high T
c
cuprates.
Received 20 April 2001 and Received in final form 13 July 2001 相似文献
12.
V.M. Khulugurov V.N. Salomatov I.M. Kalogeras A. Vassilikou-Dova I. Christakis 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):91-101
Thermally Stimulated Depolarisation Current (TSDC) and optical methods are applied to a range of alkali-fluoride crystals
in order to establish a model for the stable F
2
+
- like colour centres in LiF:OH-. The experimental results for LiF:OH- suggest that the OH- defects are partially destroyed under ionising irradiation or during crystal growth. The low-temperature dielectric relaxation
signals in LiF:OH- and LiF:Mg2+,OH- are attributed to highly interacting hydroxide ions and products of their destruction located in extended lattice defects.
In LiF:OH-, in contrast to other alkali halides, the results advocate for a defect-structure model, which considers a neutral defect
(ND, probably O2 or H2) sited at the anion vacancy of the O2--V
a
+
dipole and which possibly is the “nucleus” for the F
2
+
centre. The proposed F
2
+
(ND, O-) model seems to better explain the dielectric results, compared to the older F
2
+
(O2-) and F
2
+
(O-) models. The estimate for the electric dipole moment derived from the experimental TSDC bands, gives a value for the F
2
+
- like centre in LiF:OH- between those of the F
2
+
(O-) and F
2
+
(O2-) defects, in good agreement with the proposed F
2
+
(ND,O-) model. The reduction of the activation energy barrier of the (re)orientation process of the Mg2+V
c
-
(OH-) complexes in LiF:Mg2+,OH-, and the low-temperature shift of their TSDC band, compared to the single Mg
2
+
V
c
-
peak in LiF:Mg2+, are tentatively ascribed to an increase in the crystal-lattice parameters owing to the presence of OH- and/or products of its destruction.
Received 31 August 2001 / Received in final form 30 March 2002 Published online 9 July 2002 相似文献
13.
J.U. Andersen C. Gottrup K. Hansen P. Hvelplund M.O. Larsson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):189-204
Thermionic emission from hot fullerene anions, CN
-, has been measured in an electrostatic storage ring for even N values from 36 to 96. The decay is quenched by radiative cooling and hence the observations give information on the intensity
of thermal radiation from fullerenes. The experiments are analysed by comparison with a simulation which includes the quantisation
of photon energy and the statistics of emission. Experiments with heating of the molecules with a laser beam confirm the interpretation
of the observations in terms of radiative cooling and give an independent estimate of the cooling rate for C60
-. The measured cooling rates agree in general within a factor of two with the prediction from a classical dielectric model
of a thermal radiation intensity of ∼ 300 eV/s for C60 at 1 400 K, scaling approximately with the 6th power of the temperature and with the number of atoms in the molecule.
Received 12 March 2001 and Received in final form 12 June 2001 相似文献
14.
S.W. Ødegård B. Herskind T. Døssing G.B. Hagemann D.R. Jensen G. Sletten J.N. Wilson S. Leoni P.O. Tjøm P. Bednarczyk D. Curien 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):309-316
High-spin properties of the triaxial strongly deformed potential well in 163Lu at excitation energies above resolvable bands have been investigated. Gated E
γ-E
γ spectra display clear ridges with moments of inertia corresponding to those observed for the discrete strongly deformed bands.
A fluctuation analysis of the ridges yields a number of two-step paths of ≈ 40 and ≈ 20, when gating on triaxial strongly
or normally deformed bands, respectively. These results show that a potential well at large deformation coexists with the
normally deformed well, and indicate a mixing between states in the two wells at higher excitation energy.
Received: 4 January 2002 / Accepted: 6 May 2002 相似文献
15.
A. Bauchet I. Deloncle M.-G. Porquet A. Astier N. Buforn M. Meyer S. Perriès N. Redon B.J.P. Gall F. Hoellinger N. Schulz G. Duchêne S. Courtin Ts. Venkova P.A. Butler N. Amzal R.D. Herzberg A. Chewter R. Cunningham M. Houry R. Lucas W. Urban A. Nowak E. Piasecki J. Duprat C. Petrache T. Kröll 《The European Physical Journal A - Hadrons and Nuclei》2001,10(2):145-150
High-spin states of 103
43Tc have been identified for the first time, this nucleus being produced as fission fragment following the fusion reaction
37Cl + 176Yb at 170 MeV bombarding energy. The high-spin level scheme has been built from the prompt gamma rays detected using the Euroball
III array. It exhibits similarities with those of the neighbouring isotopes and isotones. All the band head configurations
observed in the 97-105Tc isotopes are identified from the behaviour of the rotational bands built on them. The single-proton states located around
the Fermi level are discussed as a function of deformation of these nuclei.
Received: 19 January 2001 / Accepted: 23 February 2001 相似文献
16.
G. Riou S. Jandl M. Poirier V. Nekvasil M. Diviš P. Fournier R.L. Greene D.I. Zhigunov S.N. Barilo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(2):179-182
We present an infrared crystal-field study of Pr2CuO4 single crystals and thin films. Excitations from the ground state multiplet 3H4 to the 3H5, 3H6, 3F2 and 3F3 excited multiplets are observed in both single crystals and thin films. A precise set of crystal-field parameters, that reproduces
the energy and the symmetry of the levels, is determined.
Received 25 April 2001 相似文献
17.
LiF crystals with F2
- centers contain a whole series of F-based colour centers with spectrally overlapping absorption spectra. On the short-wavelength side the absorption spectrum of the F2
- centers is overlapping with the absorption spectra of other colour centers and is therefore not directly accessible by transmission measurements. Fluorescence excitation spectroscopy is employed here to gain information on the absorption spectrum of F2
- centers in spectral regions where the absorption by other centers is present. The fluorescence signal emitted beyond 1200 nm is detected as a function of the excitation wavelength in the range from 350 nm to 1100 nm. The F2
- center absorption cross-section spectrum in the wavelength range from 690 nm to 1100 nm and from 350 nm to 410 nm is determined from the fluorescence excitation quantum distribution and the transmission spectrum. Influences of fluorescence re-absorption and Förster-type energy transfer on the fluorescence excitation quantum distribution and the subsequent F2
- center absorption cross-section determination are discussed. PACS 61.72.Ji; 78.40.Ha; 78.55.Fv 相似文献
18.
H. Skenderović R. Beuc T. Ban G. Pichler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):49-56
Three distinct satellite bands at 730-736 nm and a single shoulder at 755.5 nm that we assigned to KRb heteronuclear molecule
are found in absorption measurements of hot K + Rb vapor. The interpretation of these bands is discussed in terms of recent
ab initio calculations of the relevant potential curves. Semiclassical spectral simulations were performed with ab initio potentials and approximate transition dipole moment functions showing a good agreement with observations. The probabilities
of cold molecule photoassociative formation into the external well of the double minimum (5)0+ state and decay to the ground state are discussed, and relative yields of molecular formation were estimated by using quantum
mechanical calculations.
Received 15 October 2001 相似文献
19.
O.-H. Kwon H. Yoo D.-J. Jang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):69-75
While the intercalation of C60 and the formation of C
60
-
in the supercages of NaX and NaY are confirmed by using 129Xe NMR and ESR, the photophysical properties of C60 and C
60
-
are characterized by monitoring transient reflectance spectra and kinetics, fluorescence kinetics, and diffuse reflectance
spectra. C
60
-
is considerably more abundant in NaY than in NaX. This difference is explained in terms of polarity difference between two
zeolites. Both C60 and C
60
-
have remarkably elongated excited-state lifetimes due to their collision-free environment in zeolitic nanocavities although
C
60
-
has much shorter lifetimes than C60. C
60
-
, in particular, shows intense absorption and emission due to its reduced symmetry in zeolites.
Received 13 July 2001 and Received in final form 8 October 2001 相似文献
20.
V.V. Harutunyan V.A. Gevorkyan V.N. Makhov 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(1):35-38
The luminescence spectra of corundum monocrystals grown by different methods are investigated by means of a time-resolved
spectroscopy method at temperatures 90 K and 300 K. The existence of fast and slow emission in the VUV luminescence spectra
of irradiated and nonirradiated crystals was observed. We observed luminescence bands with a maximum at 326 nm produced by
F
+
centers. A new type of fast luminescence at the band of 270 nm was found. This is known as cross-luminescence and is connected
with the recombination of valence band electrons with the holes in the low ground band. It was shown that the band of 410
nm isn't due to to anionic centers (F-centers), but is determined by the short lifetime center of emission (F
-
-centers).
Received 20 October 1998 and Received in final form 20 January 1999 相似文献