f.c.c./f.c.c.LUCS的电子结构

在只计入最近邻间相互作用的紧束缚近似下,计算了由两种面心立方金属组成的多层超薄共格结构(LUCS)的电子能谱和态密度。 关键词：     

Chin. Phys. B Vol. 21. No. 6 （2012） 066301

[BO4]^-1＋4SIO2 → [BSi4O1o]^-1 ＋ 02, 2BaC03＋SiO2→Ba2SiO4＋2C02. The relatively higher temperature that is suffi-cient to melt the mixture was chosen to be 1100 ℃. 510 ℃ was determined as the annealing temperature to exclude stress and air bubbles.     

К ТЕОРИИ СПОНТАННОЙ Н АМАГНИЧЕННОСТИ ТОНК ИХ СЛОЕВ. I. ЧАСТЬ

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J.J.汤姆孙

J·J·汤姆孙是英国著名的物理学家,曾因气体导电的实验研究和发现电子,获1906年的诺贝尔物理学奖.他是原子物理学的主要奠基人之一,又是一位伟大的教育家,是研究生制的创立者,是现代科研中心——卡文迪什实验室的第三任卡文迪什教授. J·J.汤姆孙于1856年12月18日生于曼彻斯特     

V.A. Fassel

V.A.Fassel是美国依阿华州立大学已退休的名誉教授,美国能源部Ames试验室杰出的学者,1988年获美国化学会分析化学奖。Perkin-Elmer公司资助奖励,促进了光谱化学的发展和进步。1986年他获4000美元奖金,在美国化学会1988年9月25～30日在洛杉矶举行的秋季会议上颁发一个奖牌。Fassel早在学生时代的化学竞争中名列前茅荣获冠军,得到200美元奖金,使他有可能进入大学继续深造。Fassel在国内和国外得到     

P.W.J.M鲍曼斯逝世

著名光谱化学专家P.w.J.M鲍曼斯于2008年10月26 日逝世,享年76岁. 鲍曼斯1932年生予荷兰,于阿姆斯特丹大学化学物理系毕业.1961年获博士学位.1961～1968年间在阿姆斯特丹大学任教,从事原子光谱分析,发射光谱光源激发机理的研究.1966年出版专集:"Theory of Spectrochemical Excitation"1968年他进入Eindhoven的Philips研究实验室,曾任该实验室主任研究员     

Comment on ‘Cr LVV Auger emission and photoreduction of hexavalent Cr oxides by A.G. Schrott,G.S. Frankel,A.J. Davenport,H.S. Isaacs,C.V. Jahnes and M.A. Russak’

A paper by Schrott et al. [Surf. Sci. 250 (1991) 139] on the Auger Cr LVV spectra of Al/Cr alloys is commented on.The area of major disagreement regards the hypothesis that Al-alloying suppresses the Cr LVV decay. It is pointed out that the surface chemical composition of the alloys should be considered in detail, and that instrumental factors and the presence of surface contamination would account for the negligible Cr LVV intensity.     

On the occurrence of b.c.c.–h.c.p. structural phase transition in Mo under pressure

Abstract

To resolve the controversy on the occurrence of a b.c.c.–h.c.p. transition in shock as well as static measurements in Mo, we have done more accurate total energy electronic structure calculations. Our results show that this phasetransition should occur at much higher pressures than suggested by earlier calculations.     

Gamma transitions in the decay of195mPt

The gamma transitions in the decay of^195mPt were investigated by the use of high resolution double focusing beta-ray spectrometer. Conversion electrons were observed for transition of energy 79.94±0.32 keV and ascribed for the first time to the decay of 4.2 d^195mPt. This confirmed that the 209 keV level decays either by the 208.81 keV transition (98%) or by a 79.94 keV–128.51 keV cascade (2%). The multipolarity assignment for each transition in¹⁹⁵Pt was obtained by comparing the measured conversion line intensity ratios with the theoretical line intensity ratios ofSliv andBand. Two gamma transitions of nearly equal energy 129 and 130 keV could be detected, the first found to be pureE2 transition while the latter hasM4 character. The mixing ratio of some gamma-rays have been determined and some discrepancies were found. The data were discussed on the light of Coulomb excitation results.     

Excited states in195Pt from the decay of 2.3h195Irg, 3.7h195Ir m and 183d195Au

The decay of two previously reported isomers in¹⁹⁵Ir has been investigated with Ge(Li) and Si(Li) detectors by observing β and γ rays as well as conversion electrons in single and coincidence measurements. To about 30 of the 85 observed transitions a multipolarity was assigned. The energies of the gamma rays from¹⁹⁵Au were also determined accurately. The decay scheme of¹⁹⁵Ir shows 13 new levels in¹⁹⁵Pt between 389 and 931 keV. Probable spin and parity assignments could be made to most levels. The results are compared with those of a recent Coulomb excitation study, reaction work and theoretical calculations.     

Studies on the low-lying levels in192Pt and192Os populated in192Ir decay

Low-lying levels in¹⁹²Os and¹⁹²Pt are reinvestigated through¹⁹²Ir (73.831d) decay with improved system performance and counting statistics. Experiments show that gamma rays reported in literature with energies 1413, 1237, 1147, 911, 773, 629, 362 and 325 keV are not from the decay of¹⁹²Ir and gamma rays reported with energies 1200, 1056, 920, 904, 784 and 624 keV are resulted from sum-up or pile-up effects of low energy intensive gamma rays. New gamma-gamma coincidence relations are obtained with 105 cm³–110 cm³ germanium detector system. A level at 1384 keV is established in the decay scheme and four newly proposed levels at 1118.31 keV in¹⁹²Os and 1146.95, 1237.35 and 1413.76 keV in¹⁹²Pt are excluded from the decay scheme. Predictions of Interacting Boson Model on level energies andE2 absolute reduced transition probabilities are compared with experimental results.     

The K-, L- and M-Auger and L-Coster-Kronig spectra of platinum

The K-, L- and M-Auger and L-Coster-Kronig spectra of platinum in the electron capture decay of ¹⁹⁵Au was measured by means of the Vanderbilt iron-free, double-focussing spectrometer. The energies and relative intensities of 55 peaks were measured in the L-Auger spectrum in the energy range of 5 to 12 keV. The intensities are compared to those calculated theoretically for silver by Asaad. The total L-Coster-Kronig plus M-Auger intensity (0 to 3.25 keV) was measured relative to the L-Auger intensity. The measured relative intensities of the KLL Auger lines are compared to the theoretical and experimental results of others. The measured KLL energies agree with those calculated semi-theoretically by Hörnfeldt and by Listengarten. A value of KLX/KLL = 0.548±0.044 was measured. A measurement of the KL₃L₃(³P₀)/KL₃L₃(³P₀+³P₂) ratio, the first reported in this Z-region, gave a value of 0.095±0.024.     

Alpha-gamma decay studies of 255Rf, 251No and 247Fm

The decay of the isotopes ²⁵⁵Rf, ²⁵¹No and ²⁴⁷Fm produced in the reactions , and was investigated by means of α-γ spectroscopy. Previously observed γ transitions in coincidence with α decays of ²⁵⁵Rf were confirmed, their energies and line intensities were measured more precisely, and their multipolarities were determined as E1. In ²⁵¹No a new isomeric state at E ^* > 1700keV with a half-life of ≈ 2μs was identified. The decay of ²⁴⁷Fm was measured more precisely. A partial level scheme of the daughter nucleus ²⁴³Cf could be established.     

The conversion electron spectrum in the decay of195Au

Twenty-four internal conversion lines in the decay of¹⁹⁵Au have been studied at high resolution by means of the Vanderbilt iron-free spectrometer. The electron intensities of this work and previously published photon intensities were used to calculate the percentage decay to each level in¹⁹⁵Pt. Conversion coefficients andL subshell ratios were used to assign the following multipolarities: 30.8 keV, pureM1; 98.8 keV, (99±1)%M1; 129.8 keV, pureE2; and 210 keV, pureE2. MeasuredL subshell ratios are not in good agreement with theoretical values.     

The modified decay width of the radioactive nucleus

It is reported that the width of the first excited state ( , 37.133keV) of ¹²¹ ₅₁Sb embedded in a ZnSb alloy can be modified by reabsorption of γ -rays scattered backward on the platinum (gold) reflector. Its dependence on the reflector shape is also investigated. The decay rate is reduced about 4.5% at a temperature of 4.2K by a platinum spherical reflector of 5mm radius.     

The electron capture decay of 195Au

The decay of ¹⁹⁵Au has been investigated by means of a 4π internal source scintillation spectrometer and a Ge(Li) detector. Electron capture branching ratios and several L/K and M+…/L capture ratios have been measured. The atomic electron capture transition energy and the cross-over decay probability of the 130 keV state have been calculated.     

Odd-proton alpha-decay systematics and nuclear structure just beyond208Pb

The level structures populated in alpha decay of all odd-Z-even-N nuclei withZ=(83–93) andN=(126–142) up to 500 keV are presented. More data on the 4n+3 nuclear sequences are given from²¹⁵Bi to²³⁵Np. Particular emphasis is placed on the hindrance factors to alpha decay in interpreting the level structures in term of the shell model, the octupole-quadrupole model and the Nilsson model. The level structures and the hindrance factors go through transition region in which mixtures of the properties of two different nuclear models are appropriate. These transition regions represent a challenge to nuclear theorists to develop more all-encompassing nuclear models.