共查询到20条相似文献,搜索用时 31 毫秒
1.
D.J. Chadi 《Solid State Communications》1976,20(4):361-364
The angular momentum contents of Bloch functions for a number of group IV and zincblende crystals are examined using a pseudopotential approach. The large amplitudes for d and f character functions found even for valence electron wave functions are related to the overlap of p and s symmetry states on different atoms. In zincblende crystals the strength of the d and f components increases around cations and decreases around anions for the valence bands. The f-like component is appreciable for the Γ1 conduction band particularly around a cation. 相似文献
2.
G. Wiech 《Zeitschrift für Physik A Hadrons and Nuclei》1967,207(5):428-445
With a photon-counting concave grating spectrograph the SiL 2,3 emission bands of pure Si, SiC and SiO2 (quartz) were investigated. The observed bands are in good agreement with recent measurements using photon-counting devices but differ markedly from those obtained with photographic registration. The comparison of these SiL 2,3 bands with the corresponding SiKβ bands observed by other authors shows that the intensity distributions are more or less complementary. For Si and SiC the experimental results are compared with recent calculations of the electronic band structure. The agreement between the measuredK andL emission bands of silicon and the calculated density of states curve of silicon is satisfactory. 相似文献
3.
R. E. Ovcharenko I. I. Tupitsyn V. G. Kuznetsov A. S. Shulakov 《Optics and Spectroscopy》2011,111(6):940-948
Using the density functional method in the pseudopotential approximation, we calculate the probabilities of X-ray emission
transitions and shapes of the L
2,3 X-ray emission bands of Mg in crystals of metallic magnesium and monoxide MgO. We have paid special attention to the study
of mechanisms by which these bands were formed; therefore, along with the total intensities, we determine the partial s- and d-contributions. In addition, the intensities of the L
2,3 bands of Mg have been separated into contributions from direct (intra-atomic) transitions and charge-transfer crossover transitions.
We show that an unexpectedly large contribution of partial d-transitions in magnesium oxide is caused by crossover transitions of electrons of valence states of ligands to the core 2p-level of Mg, i.e., charge-transfer transitions. In metallic magnesium, the contribution of these transitions proved to be
insignificant. An appreciable contribution of crossover transitions has also been revealed in s-contributions of X-ray emission bands. To estimate the calculation accuracy, we have compared the shapes of theoretical spectra
with the shapes of experimental L
2,3 X-ray emission bands of Mg. 相似文献
4.
K. Maeda 《Journal of Physics and Chemistry of Solids》1982,43(2):121-123
The wavelengths and energies of the L1, L2 and L3 absorption limits in Zr, Nb, Ru, Rh, Pd and Ag metals have been measured and some of the previous reported values have been found to be incorrect. By comparing the energies of the absorption limits with those of the Lγ1Ly, and Lβ2,15, lines and also with the binding energies obtained by XPS, the electronic transitions corresponding to the respective absorption limits have been clarified. It is concluded that (i) the end level of the electronic transition corresponding to the L1 absorption limit of Zr-Ag is the 5p-like level, and (ii) the end level corresponding to either of the L2 and L3, absorption limits of Zr-Pd is the 4d level, while that of Ag is, rather unexpectedly, the top of the 5s level. 相似文献
5.
P. Zimmermann 《Zeitschrift für Physik A Hadrons and Nuclei》1969,223(2):180-191
The level-crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure of the 5s 25d 2 D 3/2- and 5s 26d 2 D 3/2-stedes of the In I-spectrum. From the shifts of the level-crossing signals due to the Stark effect of the electric field the Stark constantsβ of both states were deduced: 5s 25d 2 D 3/2: ¦β¦=0.33(3) Mc/(kV/cm)2 5s 26d 2 D 3/2: ¦β¦=6(1) Mc/(kV/cm)2. By theoretical calculations with wave functions of the Coulomb approximation one can show, that the Stark effect in both states is mainly due to admixtures of the 5s 26p- resp.5s 27p-configuration. 相似文献
6.
V. V. Bolotov K. E. Ivlev P. M. Korusenko S. N. Nesov S. N. Povoroznyuk 《Physics of the Solid State》2014,56(6):1256-1260
The changes in the electronic structure and phase composition of porous silicon under action of pulsed ionic beams have been studied by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) using synchrotron radiation. The Si 2p and O 1s core photoemission spectra for different photoelectron collection angles, valence band photoemission spectra, and X-ray absorption near-edge fine structure spectrain the region of Si L 2,3 edges of the initial and irradiated samples have been analyzed. It has been found that, as a result of the irradiation, a thin oxide film consisting predominantly of higher oxide SiO2 is formed on the porous silicon surface, which increases the energy gap of the silicon oxide. Such film exhibits passivation properties preventing the degradation of the composition and properties of porous silicon in contact with the environment. 相似文献
7.
The intensity distribution of Kβ- and L2,3-emission bands of pure silicon and silicon in MoSi2, Mo5Si3 and Mo3Si are investigated. Some of the aspects of the electronics structure of these compounds are discussed. 相似文献
8.
9.
《Journal of Quantitative Spectroscopy & Radiative Transfer》1986,36(1):7-18
Transition probabilities of 211 spectral lines of VII, in the wavelength range 2340–4200 Å, have been determined by emission spectroscopy using a wall-stabilized arc as source. The lines studied belong to the transition arrays 3d4, 3d34s-3d34p (199 lines) and 3d34p-3d34d, 3d35s (12 lines). Vanadium was introduced into the helium-arc discharge as the liquid VOCl3. An important feature of this work is the determination of transition probabilities for many lines from a wide spectral range with a uniform absolute scale. The absolute Aki values were obtained by normalizing relative Aki values to an absolute scale set by ionic lifetime for the level y3H04. These results are compared with other experimental as well as theoretical results. 相似文献
10.
V.V. Nemoshkalenko V.P. Krivitskii A.P. Shpak L.I. Nikolajev 《Solid State Communications》1974,15(1):9-11
The intensity distribution of the Kβ-and L2,3-emission bands of pure silicon and silicon in ZrSi2, Zr3Si2, Zr5Si3 and Zr3Si are investigated. Some of the aspects of the electronic structure of these compounds are discussed. 相似文献
11.
G. Wiech 《Solid State Communications》1984,52(9):807-809
The silicon K and L2,3 X-ray emission bands of stishovite (tetragonal SiO2, 6:4 co-ordination) are reported and discussed along with the corresponding emission bands of α-quartz (hexagonal SiO2, 4:2 co-ordination). While the shapes of the Si K-emission bands of stishovite and α-quartz differ considerably, those of the Si L2,3-emission bands are similar. The measured spectra are compared with theoretical band structure calculations, and good overall agreement is found. 相似文献
12.
Charles C. Gallagher Morton A. Levine 《Journal of Quantitative Spectroscopy & Radiative Transfer》1975,15(3):275-279
Time-resolved measurements of satellites about the (1s2s?1s3d) forbidden transition in helium, satellites both of the Hδ line of hydrogen and of its splittings and, finally, satellites of He II 4868 Å have been observed. The behavior of these satellites is correlated relative to each other and to previously reported satellites both on Hβ and near the 6632 Å (1s2p?1s3p) forbidden transition in helium. The appearance of the satellites is attributed to a strong field interaction between orthogonal components of the dynamic and quasistatic electric fields generated in a plasma by an instability. 相似文献
13.
The optical absorption spectra of MnCl2, FeCl2, CoCl2, and NiCl2 have been measured over the energy range from 2 to 30 eV. The gross features of the spectra, especially broad bands above 10eV, are alike in all of the four materials. The charge transfer bands due to the electronic transitions from the 3p level of chlorine to the 3d and 4s levels of metal ions and the band due to the 3d → 4s transition are assigned in the spectra. 相似文献
14.
E. Tegeler M. Iwan E.-E. Koch 《Journal of Electron Spectroscopy and Related Phenomena》1981,22(3):297-307
The soft X-ray emission and photoelectron emission spectra of H2-, Mg- and Pt- phthalocyanine (PC) obtained using synchrotron radiation are reported and compared. In this way, an overall view of the pattern of valence bands is obtained and the electronic structure determined in terms of the component partial densities of states. In particular, from the valence p → 1s carbon and nitrogen K-emission spectra we determine for all three compounds the C and N 2p-like valence-band density of states with strong maxima located at binding energies of 8, 11 and 13.5 eV (carbon 2p) and 8 eV (nitrogen 2p) below the vacuum level. For PtPC the partial density of d-like valence states is determined from photoelectron emission difference-spectra and compared to previous XPS results. The sharp (1.2 eV FWHM) maximum of the Pt-derived partial density of states, observed at 6.9 eV binding energy, is assigned to the 4F term of a 5d86s final-state configuration. A second, broader maximum at around 9.5 eV binding energy contains contributions from other terms of this 5d8 configuration, as well as from a 5d7 satellite (shake-up multiplet). 相似文献
15.
Wave functions obtained in previous shell-model calculations [1, 2] for states of nuclei with massesA=10–15 are used to calculate logft values and spectroscopic factors. These wave functions, which were based on a modified surface delta two-body interaction, comprise the following active shell-model spaces: the 1p 3/2 and 1p 1/2 orbitals for mass 10–14 nuclei and restricted combinations of the 1p 1/2, 2s 1/2, 1d 5/2 and 1d 3/2 orbitals for mass 15 nuclei, leading to four different calculations in the latter case. The calculated results support evidence that the modified surface delta interaction is a valid approximation to the effective interaction in light nuclei. 相似文献
16.
K. Maeda 《Journal of Physics and Chemistry of Solids》1981,42(11):981-983
The paper consists of two parts. (1) The author studied the mechanism of the appearance of the double discontinuities of wide separation in the X-ray L1 absorption spectrum of Mo in MoO3, which were found in the recent research about the effects of chemical combination on various X-ray absorption limits, and that of Nb in Nb2O5. Then he arrived at the conclusion that the discontinuity of the higher energy corresponds to the electronic transition from L1 to 5p, and that of the lower energy is attributed to that from L1 to the 4d, 5s state. (2) The author applied the explanation to the double discontinuities which have been observed by many researchers in the K absorption spectra of 3d transition elements in highly oxidized compounds, and showed that these double absorption discontinuities are ascribed to the electronic transitions K?4p and K ? 3d, 4s. 相似文献
17.
《Journal of Quantitative Spectroscopy & Radiative Transfer》1986,36(1):19-37
Dipole transition probabilities connecting the 1s22s22p3(4S0)nl3,5LJ levels are presented for (nl) up to (15,5). The calculations are based on the single-configuration Hartree-Fock wave functions with the 1s and 2s orbitals treated as a frozen core. The results generally agree well with earlier works (theoretical and experimental) on transitions involving low quantum numbers. 相似文献
18.
R. -H. Rinkleff 《Zeitschrift für Physik A Hadrons and Nuclei》1978,288(3):233-239
The level-crossing technique with parallel electric and magnetic fields was used to measure the tensor polarizabilities of six levels of the configuration 4f 13 6s6p + 4f 12 5d6s 2 in the Tm I-spectrum. Using intermediate coupling wave functions given by Camus and the experimental values of the tensor polarizabilities, the radial integrals for electric dipole transitions from levels of the configuration 4f 136s6p + 4f 125d6s 2 to levels of the configuration 4f 13 5d6s + 4f 12 6s 26p have been determined. The results areI(4f 136s6p,4f 135d6s)=1.98(45)ea 0 andI(4f 125d6s 2,4f 126s 26p) = 0.88(25)ea 0. A comparison between the experimental and the calculated values of the tensor polarizabilities shows an excellent agreement, provided that these radial integrals and the radial integrals for the electric dipole transitions to the ground state configuration 4f 136s 2 as determined by Wallenstein from lifetime measurements are used in the calculation, instead of radial integrals computed by Camus with Hartree-Fock wave functions. 相似文献
19.
P. Streubel R. Fellenberg A. Reif 《Journal of Electron Spectroscopy and Related Phenomena》1984,34(3):261-274
Chemical shifts of Auger transitions and photoelectron binding energies of silicon have been measured and interpreted using the quasi-atomic approach. The Si KL2,3L2,3 and L2,3V1V1 Auger transitions and the binding energies of Si 2p and of the valence electrons at the maximum of the density of states V1 have been investigated in solid silicon and in the compounds SiC, Si3N4, SiO2, Na2SiF6 and T3Si (T = V, Cr, Mn, Fe, Co, Ni). The relaxation-energy shift ΔReaS(2p, 2p) describing the polarization effect (final-state effect) has been evaluated by AES and XPS measurements. Furthermore, the extra-atomic relaxation energy ReaD(2p) of the 2p electrons has been determined experimentally for silicon atoms in differing environments. This allows estimation of the potential parameter V(2p) describing the potential effect (initial-state effect). In general ReaD(2p) was found to be more sensitive to changes in chemical bonding than V2p). The behaviour of the quasi-atomic Si V1 electrons seems to be the converse. 相似文献
20.
Surfaces of mineral cuprite prepared by fracture under UHV have been characterised by synchrotron XPS and near-edge X-ray absorption spectroscopy before and after exposure to ambient air. Before exposure of the cuprite, the Cu 2p photoelectron and Cu L2,3-edge absorption spectra were consistent with CuI with very little d9 character. Surface-enhanced O 1s spectra from the unexposed mineral revealed a surface species, with binding energy 0.95 ± 0.05 eV below the principal cuprous oxide peak, assigned to under-coordinated oxygen. A second surface species, with binding energy about 1 eV higher than the principal peak, was assigned to either hydroxyl derived from chemisorbed water vapour or surface oxygen dimers produced by restructuring of the cuprite fracture surface. The width of the principal O 1s peak was 0.66 ± 0.02 eV. The observed Cu L3- and O K-edge absorption spectra were in good agreement with those simulated for the cuprite structure. After exposure of the fracture surface to ambient air, the low binding energy O 1s surface species was barely discernible, the original high binding energy O 1s surface species remained of comparable intensity, new intensity appeared at an even higher (∼1.9 eV) binding energy, and the Cu L2,3-edge spectrum indicated the presence of CuII, consistent with the formation of a thin surface layer of Cu(OH)2. 相似文献