共查询到20条相似文献,搜索用时 62 毫秒
1.
V. Vaithianathan K. Asokan Jae Young Park Sang Sub Kim 《Applied Physics A: Materials Science & Processing》2009,94(4):995-998
Using X-ray absorption near-edge structure spectroscopy (XANES), we investigate the local electronic structure of phosphorus
(P) and its chemical valence in laser-ablated n-type (as-grown), and p-type (annealed) P-doped ZnO thin films. Both the P L
1- and P L
2,3-edge XANES spectra reveal that the valence state of P is 3− (P3−) in the p-type as well as in the n-type P-doped ZnO. However, the peak intensity is stronger in the former than that in the latter, suggesting that P replaces O
(O2− sites with the P3−) after rapid thermal annealing. The Zn and O K-edges XANES spectra consistently demonstrate that, in the p-type state, P ions substitutionally occupy O sites in the ZnO lattice. 相似文献
2.
Summary Room temperature optical-reflectivity measurements on some transition metal thiophosphates were carried out in the near infrared
and visible regions. The resulting spectra, interpreted on the basis of the ?transition metal weakly interacting? model, agree
well with earlier optical transmission measurements. Below the fundamental absorption edge, the observed features have been
assigned to 3d–3d transitions occurring on the transition metal ion, while those observed at photon energies greater than the absorption threshold
have been attributed to transitions from the valence bands to discrete 3d orbital levels or to the conduction bands. A more detailed information on the metal ion 3d levels energy distribution with respect to the valence band states belonging to the (P2S6)4- cluster and a more precise determination of the MPS3 absorption edge energy position have been obtained. 相似文献
3.
M. Piacentini V. Grasso S. Santangelo M. Fanfoni S. Modesti A. Savoia 《Solid State Communications》1984,51(7):467-472
With the partial yield technique we measured the absorption spectra of several core levels in FePS3 and NiPS3. The M2, 3 spectra of Fe and Ni are interpreted as localized transitions 3p63dm?3p5 3dm+1 of the transition metal ion, split into a multiplet by final state multiconfiguration interaction. The P L2, 3, S L2, 3, and S L1 spectra are similar to each other and are interpreted in terms of the projected density of states of the conduction bands derived from the states of the (P2S6)4? cluster. 相似文献
4.
Polycrystalline MgxAl2xLi0.5(1−x)Fe2.5(1−x) O4 (x = 0.0, 0.2, 0.5, 0.6 and 0.7) ferrites were prepared by standard ceramic method, and characterized by X-ray diffraction and
infrared absorption spectroscopy. The spectra show two significant absorption bands in the wave number range of 400–1000 cm−1 arising from interatomic vibrations in the tetrahedral and octahedral coordination compounds. The decrease in intensity and
increase in broadness of bands with concentration (x) are explained on the basis of cation distribution. The force constants and bulk modulus are found to decrease with Mg-Al
content (x) which suggested weakening of interatomic bonding. An alternate method for the determination of bulk modulus, longitudinal
and transverse velocities is suggested. The magnetic and electrical properties of these compounds are explained in the light
of structural and optical properties. 相似文献
5.
Infrared (IR) and UV spectra of ternary Li2O–CuO–P2O5 glasses in two series Li2O(65−X)%–CuO(X%)–P2O5(35%), X = 20, 30, 40 and Li2O(55−X)%–CuO(X%)–P2O5(45%), X = (10, 20, 30) were studied. Infrared (IR) investigations showed the metaphosphate and pyrophosphate structures and with
increase of CuO content in metaphosphate glass, the skeleton of metaphosphate chains is gradually broken into short phosphate
groups such as pyrophosphate. IR spectra showed one band at about 1,220 and 1,260 cm−1 for P2O5(35%) and P2O5(45%) series, respectively, assigned to P=O bonds. For CuO additions ≤20 mol%, the glasses exhibit two bands in the frequency
range 780–720 cm−1 which are attributed to the presence of two P–O–P bridges in metaphosphate chain. But for CuO addition ≥30 mol%, the glasses
exhibit only a single band at 760 cm−1 which is assigned to the P–O–P linkage in pyrophosphate group. In optical investigations, absorption coefficient versus photon
energy showed three regions: low energy side, Urbach absorption, and high energy side. In Urbach’s region, absorption coefficient
depends exponentially on the photon energy. At high energy region, optical gap was calculated and investigations showed indirect
transition in compounds and decreases in optical gap with increases of copper oxides contents that is because of electronic
transitions and increasing of nonbridging oxygen content. 相似文献
6.
The photoconductivity (PC) spectra and the induced absorption of background radiation in the energy range 10–40 meV are investigated
in weakly compensated B-, Ga-, and As-doped silicon at 4.2 K. It is shown that dips corresponding to the photoionization of
long-lived excited states of B and As are observed in the PC spectra on the D
−(A
+) bands. It is found that the frequency dependence of the PC spectra corresponds to excitation relaxation times of the order
of 10−4 s for the states in the D
− (A
+) bands. It is established that in electric fields E>100 V/cm the PC decreases sharply, while the induced absorption of the background radiation changes very little. This confirms
the conclusion that the excitation of the D
− (A
+) itself makes the main contribution to the PC.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 224–227 (25 August 1997) 相似文献
7.
A. S. Shkvarin Yu. M. Yarmoshenko N. A. Skorikov M. V. Yablonskikh A. I. Merentsov E. G. Shkvarina A. N. Titov 《Journal of Experimental and Theoretical Physics》2012,114(1):150-156
The electronic structure and the chemical bond in titanium dichalcogenides TiX2 (X = S, Se, Te), which are promising electrode materials for lithium batteries, are studied experimentally and theoretically.
It is found that the X-ray photoelectron spectra of the valence bands and the core levels of titanium and its X-ray L
2, 3 absorption spectra demonstrate a change in the ionic and covalent components of the chemical bond in these compounds. The
densities of states in these compounds are calculated by the full-potential augmented-plane-wave method, and multiplet calculations
of the X-ray L
2, 3 absorption spectra of titanium are performed. It is shown that, in the row TiS2-TiSe2-TiTe2, the covalence increases, the ionicity of the chemical bond decreases, and the effect of the crystal field of a ligand is
weakened. 相似文献
8.
W H Madhusudan Sheelavathi Kollali P R Sarode M S Hegde P Ganguly C N R Rao 《Pramana》1979,12(4):317-329
X-ray and ultraviolet photoelectron spectroscopy as well as x-ray absorption spectroscopy have been employed to investigate
transition metal oxide perovskites of the general formula ABO3 (A = La or rare-earth ion, B=trivalent transition metal ion). Systematics in the core levels and in the valence bands in
the series of LaBO3 compounds have been discussed. Lanthanum chemical shifts in the x-ray absorption spectra in this series show interesting
trends. Photoelectron spectra of the solid solutions, LaNi1−x
Co
x
O3, LaNi1−x
Fe
x
O3 and LaFe1−x
Co
x
O3 show that the rigid band model is applicable to these systems. It is shown that x-ray photoelectron spectroscopy can be employed
to identify multiple oxidation states of transition metal ions in oxide perovskites.
Communication No. 30 from the Solid State and Structural Chemistry Unit.
An erratum to this article is available at . 相似文献
9.
V. S. Pavlovich 《Journal of Applied Spectroscopy》2006,73(3):328-339
A detailed derivation is presented for relations making it possible to describe the effect of temperature on the halfwidth
of the P960 and P870 absorption bands and also on the electron transfer (ET) rate at reaction centers (RCs) of the purple
bacteria Rps. viridis and Rb. sphaeroides. Primary electron transfer is considered as a resonant nonradiative transition between
P* and P+B
L
−
states (where P is a special pair, BL is an additional bacteriochlorophyll in the L branch of the reaction center). It has been shown that the vibrational hα mode with frequency 130–150 cm−1 controls primary electron transfer. It has been found that the matrix element of the electronic transition between the states
P* and P+B
L
−
is equal to 12.7 ± 0.9 and 12.0 ± 1.2 cm−1 for Rps. viridis and Rb. sphaeroides respectively. The mechanism is discussed for electron transport from P* and BL and then to bacteriopheophytin HL.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 294–303, May–June, 2006. 相似文献
10.
The infrared absorption spectra of 2,3- and 3,5-dichloroanilines have been recorded in the region 250–4000 cm−1. The spectra of the latter are recorded in solid phase (KBr and Nujol mull) and in CS2/CCl4 and CHCl3 solutions while that of the former in thin film only. The spectra have been analysed assuming C
3
and C2v
point group symmetry respectively and a tentative assignment of the observed bands to different fundamental modes has been
made. 相似文献
11.
A. S. Shkvarin Yu. M. Yarmoshenko N. A. Skorikov A. I. Merentsov A. N. Titov P. A. Slepukhin D. E. Marchenko M. Sperling 《Journal of Experimental and Theoretical Physics》2011,112(1):87-93
Cr
x
Ti1 − x
Se2 (x = 0–0.83) solid solutions have been synthesized. Single crystals have been grown in the range of concentrations x = 0–0.83. Structural studies of samples have revealed that chromium atoms substitute titanium in the TiSe2 matrix. The X-ray photoelectron spectra of the core levels, the resonance spectra of the valence bands in 1T-Cr
x
Ti1 − x
Se2, and the X-ray absorption spectra of titanium and chromium are studied. The titanium and chromium atoms are shown to have
oxidation numbers of +4 and +3, respectively, in an identical octahedral environment. The local density of chromium states
has been calculated. The results of the calculation agree well with the experimental data and indicate that the electronic
3d states of chromium substituting titanium in the matrix are spin-polarized and the density of chromium states is halfmetal
magnet in behavior. 相似文献
12.
L. Kovács M. Mazzera E. Beregi R. Capelletti 《Applied physics. B, Lasers and optics》2009,94(2):273-277
Several weak absorption bands have been observed in the optical absorption spectra of pure and rare-earth-doped YAl3(BO3)4 single crystals in the 3350– 3650 cm−1 wave number region. Two of them, peaking at about 3377 cm−1 and 3580 cm−1 in the 8 K spectra, appear in most of the samples. They are tentatively attributed to the stretching mode of OH− ions incorporated in the crystal during the growth. An additional absorption band at about 5250 cm−1 at 8 K has also been detected in almost all samples. The temperature and polarization dependences of these bands, and their
possible origin, are discussed. 相似文献
13.
Aleksandr Kalinko Alexey Kotlov Alexei Kuzmin Vladimir Pankratov Anatoli I. Popov Liana Shirmane 《Central European Journal of Physics》2011,9(2):432-437
The photoluminescence spectra and luminescence excitation spectra of pure microcrystalline and nano-sized ZnWO4 as well as the Zn
x
Ni1−x
WO4 solid solutions were studied using vacuum ultraviolet (VUV) synchrotron radiation. The samples were also characterized by
x-ray powder diffraction. We found that: (i) the shape of the photoluminescence band at 2.5 eV, being due to radiative electron
transitions within the [WO6]6− anions, becomes modulated by the optical absorption of Ni2+ ions in the Zn
x
Ni1−x
WO4 solid solutions; and (ii) no significant change in the excitation spectra of Zn0.9Ni0.1WO4 is observed compared to pure ZnWO4. At the same time, a shift of the excitonic bands to smaller energies and a set of peaks, attributed to the one-electron
transitions from the top of the valence band to quasi-localized states, were observed in the excitation spectrum of nano-sized
ZnWO4. 相似文献
14.
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
15.
A. P. Menushenkov A. A. Yaroslavtsev O. V. Grishina R. V. Chernikov A. G. Kuchin 《JETP Letters》2011,94(3):187-191
The rearrangement of the local environment of cerium has been examined using extended X-ray absorption fine structure spectroscopy
above the K-Ce absorption edge for various manganese contents and temperatures in Ce2Fe17 − x
Mn
x
intermetallics (x = 0, 1, 2). The valence state of cerium has been studied simultaneously by X-ray absorption near-edge structure spectroscopy
above the L
3-Ce absorption under the same conditions. A correlation has been revealed between the changes observed in the local electronic
and crystal structure of Ce2Fe17 − x
Mn
x
compounds and the types of magnetic states in them. 相似文献
16.
Krishnamurthy V. V. Suzuki M. Kawamura N. Ishikawa T. Kohori Y. 《Hyperfine Interactions》2001,136(3-8):361-365
The formation of an induced 5d magnetic moment on Ir in Fe97Ir3, Co95Ir5 and Ni95Ir5 alloys has been investigated by X-ray magnetic circular dichroism (XMCD) and X-ray absorption spectra (XAS) measurements
at Ir L
2,3 edges. Using a sum rule which relates the integrals of these spectra with the ground state expectation value of the orbital
angular momentum 〈L
Z
〉 of the probed atom, the orbital moment m
orb of Ir could be determined as −0.071(2) μ
B
in an Fe host, −0.067(2) μ
B
in a Co host and −0.041(1) μ
B
in a Ni host. The spin magnetic moment m
spin of Ir is also found to be the maximal in Fe and the minimal in Ni. The total moment of Ir is found to be approximately 1/5
of total moment of Fe, 2/13 of the total moment of Co, and 1/4 of the total moment of Ni.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
17.
Auger electron spectra of clean Mg and Fe surfaces have been investigated under UHV conditions. The main Auger peaks in the low energy Auger spectra of these elements are identified as due to L2,3VV and M2,3VV transitions for Mg and Fe respectively. Changes in the low energy spectra of these clean surfaces of Mg and Fe due to chemisorption of residual oxygen in the UHV system, were also studied. The results indicate that for each oxidised surface new larger Auger peaks appear at energies lower than the original main peaks in the clean spectra. The changes in the spectra are believed to be due to the energy shifts of inner energy levels and valence bands involved in the Auger transitions as an oxide is formed. 相似文献
18.
Methods of quantum chemistry (including the method of intermediate neglect of differential overlap (INDO)) are used to calculate
and to interpret the absorption and fluorescence spectra of the 9-11-dehydroderivative 2,3-dimethoxy-8-aza-D-homogon-1,3,5(10),13-tetraene-12,17a-dion
(DA-1) molecule in aproton and proton-donor solvents. The electronic structure and spectra of electronically excited states of
the isolated molecule and its complexes with water and proton solvates are calculated. It is demonstrated that bands in the
absorption spectra are complex; they are formed by two or more electron transitions. It is established that only the charged
DA-1 + H
5
O
2
+ and DA-1 + 2H
3
O
+ complexes can fluoresce.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 3–9, June, 2006. 相似文献
19.
é. P. Domashevskaya S. A. Storozhilov S. Yu. Turishchev V. M. Kashkarov V. A. Terekhov O. V. Stogne Yu. E. Kalinin A. V. Sitnikov S. L. Molodtsov 《Physics of the Solid State》2008,50(1):139-145
The electronic structure and phase composition of (Co41Fe39B20)
x
(SiO2)1 − x
nanocomposites are studied by x-ray absorption near-edge spectroscopy, which is extremely sensitive to the chemical environment
of elements in multicomponent compounds. An analysis of the recorded Fe L
2, 3, Co L
2, 3, B K, Si L
2, 3, and O K absorption spectra demonstrates interatomic interactions between the elements of the metallic and dielectric components of
the nanocomposites. As a result of these interatomic interactions, a complex multiphase system, whose electronic structure
should determine the transport and magnetic properties of the nanocomposites, forms. In particular, the transformation of
the fine structure of the iron L
2, 3 spectra reflects a change in the ratio of divalent to trivalent iron in its oxides and/or silicates. CoO and complex boron
oxides are found to exist in the nanocomposites. The electrical conductivity of a FeO · F2O3 · CoO grain embedded in the silicate-oxide medium of the nanocomposites is controlled by electron exchange between Co2+, Fe2+, and Fe3+ ions. The dielectric component consists of a mixture of silicon oxide and the silicates/borosilicates of transition metals.
Original Russian Text ? é.P. Domashevskaya, S.A. Storozhilov, S.Yu. Turishchev, V.M. Kashkarov, V.A. Terekhov, O.V. Stogneĭ,
Yu.E. Kalinin, A.V. Sitnikov, S.L. Molodtsov, 2008, published in Fizika Tverdogo Tela, 2008, Vol. 50, No. 1, pp. 135–141. 相似文献
20.
Summary A comparison is performed between theoretical and experimental shapes of theXVV (X=M
2,3 andL
3) Auger spectra of ferromagnetic Fe
x
−Ni1−x
alloys forx=0.48 and 0.27 in order to check if recent theories, which take into account the Coulomb correlation between the two final
Auger holes, would be able to reproduce shape and position of the experimental peaks in an accurate way. For the case under
investigation, it seems that, at least for the low-energy (M
2,3
VV) spectra and notwithstanding the usual neglecting of matrix element effects, the theory gives results in close agreement
with the experimental data. The comparison with the high-energyL
3
VV spectra is somewhat hampered by an asymmetric broadening of the experimental data on the low kinetic-energy side due to satellite
structures, but still gives good agreement on the high kinetic-energy side.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献