共查询到20条相似文献,搜索用时 15 毫秒
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Abstract The near infra-red absorption peaks due to transition metal ions in four halides of Fe, Co and Ni have been studied as a function of pressure. The behaviors of these ions' absorption peaks under pressure are found to be quite different. While the energy of the absorption peak in Col2 increases with pressure similar to the behavior of transition metal ions in cubic crystal fields, the absorption peaks in the Fe halides are found to be almost independent of pressure. In Nil2 two absorption peaks exhibit level-crossing at about 2GPa. The results have been interpreted in terms of a theory proposed by da Silva and Falicov [Phys. Rev. B 45,11511 (1992)] in which pressure changes the trigonal component of the crystal field at the transition metal ions. 相似文献
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M. A. Uddin A. K.F. Haque K. R. Karim A. K. Basak F. B. Malik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(3):361-369
A modification of the Kolbensvedt model, MKLV, in terms of ionic, correlation
(between the incident and target electrons) and relativistic corrections, is
proposed to calculate the K-shell electron impact ionization cross-sections
of neutral and ionic targets. The modified model, with a single set of
parameters, is found to reproduce satisfactorily the experimental data
for the neutral H, Al, Ar, Mn, Ge, Mo, Ag, Sn, Au, Bi and U and ionic Li+,
B4+ and O7+
targets better than the existing empirical models from threshold energies
to as high as 104 MeV. For the Ag target, the calculations from MKLV
follow closely the results of Scofield, and for Au, those of Scofield, and Ndefru
and Malik, both done in the relativistic Born approximation
with the
M?ller interaction, at energies higher than the peak region. 相似文献
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Abstract The local magnetic behaviours of isolated Fe and Ni impurities in the II-VI semiconductors ZnS and ZnTe have been studied directly after recoil implantation. From the measured magnetic properties, which are detected by the observation of the perturbed angular distribution, orbital contributions to the hyperfine field as well as contributions from spin magnetism are found to be present at both impurities. The interpretations on the basis of the intermediate ligand field model suggest that Fe and Ni ions are found to exist in 2+ and in 1+ states and that electronic excitations may play a significant role even microseconds after the implantation. 相似文献
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Binding-energy spectra obtained using the dipole (e, 2e) electron impact coincidence method have been used to derive the 3s/3p cross-section ratios for the photoionization of argon up to 75 eV. The 3s and 3p photoionization branching ratios have been obtained by making use of recently determined double photoionization yields. The partial photoionization cross-section (oscillator strength) for 3s ionization, obtained using the branching ratio and the known total photoionization cross-section, shows the deep minimum ca. 10 eV above threshold which has been predicted by those theoretical calculations which include electron correlation effects. Below 50 eV the cross-section is in excellent agreement with the SRPAE calculation. The results are in close agreement with recent measurements made using synchrotron radiation but are consistently smaller below the minimum and larger at the higher energies. 相似文献
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ICP-AES测定微硅粉中Ca、Mg、Fe和Al的含量 总被引:1,自引:0,他引:1
微硅粉样品经氢氟酸、硝酸、高氯酸消解,电感耦合等离子体-原子发射光谱法(ICP-AES)测定Ca、Mg、Fe、Al杂质元素含量。方法的回收率为:Ca 95.2%—100.3%,Mg 96.2%—99.6%,Fe 95.8%—97.2%,Al 98.6%—104.6%,精密度在1.50%—2.59%之间。本方法线性范围宽、分析效率高、具有良好的准确性和精密度,能快速准确地测定微硅粉中Ca、Mg、Fe和Al杂质元素的含量。 相似文献
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Y. Awaya M. Akiba T. Katou Hidekazu Kumagai Y. Tendow K. Izumo T. Takahashi A. Hashizume M. Okano T. Hamada 《Physics letters. A》1977,61(2):111-113
The K X-rays from the target elements due to N-ion bombardment are measured with a crystal spectrometer. Some aspects owing to high incident energy are discussed. The Kα satellite, Kα hypersatellite and Kβ satellite peak spacings are obtained. 相似文献
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X射线荧光光谱法测定工业硅中铁、铝、钙 总被引:6,自引:3,他引:6
通过压片法制备样片,用X射线荧光光谱法测量工作硅中铁,铝,钙,探讨了样片制备条件,并通过加入粘接剂提高了样片牢固度,用经验系数法进行元素间增强和吸收校正,经对样品制备精密度及测量准确度分析,X射线荧光光谱法测量准确度和精密度能满足传统化学法要求。 相似文献
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The effect of indirect transitions on two nucleon transfer between heavy ions and their Q-dependence
Strong contributions from indirect transitions are predicted which lead to rather broad flat angular distributions up to the grazing angle in contrast to the strong peak at the grazing angle usually expected in heavy ion reactions. The ratio of indirect to direct amplitudes increases as the Q of the reaction departs from the optimum value. 相似文献
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P. Schneider A. Nagel K. H. Bodenmiller S. Buhl 《Zeitschrift für Physik A Hadrons and Nuclei》1972,253(4):309-313
Ten gamma-ray transitions have been observed in the54Fe(3He,n γ)56Ni reaction. A new level at 3925±10 keV is established in56Ni. Spin-parity assignments of 0+, 4+ and 2+ are proposed for the levels at 3.925, 3.958 and 5.352 MeV, respectively. Branching ratios are given. 相似文献
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L.S. Caputi E. Colavita M.De Crescenzi S. Modesti L. Papagno R. Scarmozzino R. Rosei E. Tosatti 《Solid State Communications》1981,39(1):117-122
Electron energy loss measurements have been carried out in the reflection mode from polycrystalline iron. The observed structures are interpreted as surface and bulk collective losses by observing their dependence on the primary electron energy and surface oxidation. Interband transitions in the range 2–30 eV are pinpointed and found to be in excellent agreement with previous optical results, except for a new strong transition around 10 eV, which is not found in optical experiments. This transition is tentatively identified with a dipole-forbidden process, which becomes allowed because of finite momentum transfer by the electrons. 相似文献
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陈世忠 《光谱学与光谱分析》2005,25(10):1697-1699
以聚四氟乙烯(PTFE)悬浮体为化学改进剂,采用原位分离基体电热蒸发电感耦合等离子体原子发射光谱法(ETV-ICP-AES)测定了二氧化锆中痕量杂质Fe,Al和Ni.考察了灰化温度、灰化时间、蒸发温度、基体浓度等因素对待测物信号强度的影响.在优化实验条件下,方法的检出限为4.2ng·mL-1(Al)~11ng·mL-1(Fe),相对标准偏差为3.1%(Al)~4.9%(Ni). 相似文献
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Sara J. Palmer Ray L. Frost Henry J. Spratt 《Journal of Raman spectroscopy : JRS》2009,40(9):1138-1143
Hydrotalcites of formula Mg6(Al,Fe)2(OH)16(CO3)·4H2O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio have been successfully synthesised. The XRD patterns show variation in the d‐spacing attributed to the size of the cation. Raman and infrared bands in the OH stretching region are assigned to (1) brucite layer OH stretching vibrations, (2) water stretching bands and (3) water strongly hydrogen bonded to the carbonate anion. Multiple (CO3)2− symmetric stretching bands suggest that different types of (CO3)2− exist in the hydrotalcite interlayer. Increasing the cation ratio (Mg/Al,Fe) resulted in an increase in the combined intensity of the two Raman bands at around 3600 cm−1, attributed to Mg OH stretching modes, and a shift of the overall band profile to higher wavenumbers. These observations are believed to be a result of the increase in magnesium in the structure. Raman spectroscopy shows a reduction in the symmetry of the carbonate, leading to the conclusion that the anions are bonded to the brucite‐like hydroxyl surface and to the water in the interlayer. Water bending modes are identified in the infrared spectra at positions greater than 1630 cm−1, indicating that water is strongly hydrogen bonded to both interlayer anions and the brucite‐like surface. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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V. A. Gorbunov L. I. Kurkina 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(4):515-519
The size dependence of the electronic structure of Al clusters containing 3d impurity atoms, Fe, Co and Ni, has been self-consistently calculated within the model of an atom built-in in a spherical jellium cluster and the local-density functional theory. It is found that the electronic structure of Al jellium clusters containing an impurity 3d atom at the center periodically changes with an increase in cluster size. 相似文献
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X-射线荧光光谱法测定溶样后熔融制样金属硅中铁、铝、钙、钛、磷、铜 总被引:9,自引:3,他引:6
本文提出了溶解、蒸干然后用熔剂熔融残渣的样品制备方法,解决了金属硅不易直接熔融制样的难题,可以同时测定金属硅中多种杂质元素,消除了基体效应的影响,克服了标准样品对测定的限制,测定范围广,准确度高,通过安排正交试验确定了样品制备条件。 相似文献