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941.
M. Hengsberger P. Segovia M. Garnier D. Purdie Y. Baer 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(4):603-608
We present high-resolution photoemission data from the Bi(111)-surface. The electronic structure of the semimetal close to
the Fermi level has been found to change dramatically with respect to the well established bulk band structure. The Fermi
surfaces observed for the electron and hole bands resemble those of the next group-V element, antimony, probably as a consequence
of surface relaxation. This results in a relatively high surface charge density. The observed temperature dependence of the
electron Fermi energy confirms this result.
Received 8 June 2000 相似文献
942.
J. G. Tischler H. A. Nickel B. D. McCombe B. A. Weinstein A. B. Dzyubenko A. Yu. Sivachenko 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
Applied hydrostatic pressure modifies the Coulomb bound states of a quasi-two-dimensional electron gas in quantum wells by increasing the effective mass and by tuning the free electron density. Here, we explore these mechanisms by measuring the effects of pressure on the cyclotron resonance, the D0 1s → 2p+ transition, and the D−-singlet and singlet-like transitions in low-and high-density, modulation-doped GaAs quantum wells. For low doping density, detailed calculations employing a pressure-dependent electron mass agree well with the observed magnetic field and pressure dependencies. For high doping density and low fields, the blue-shift of the D−-singlet-like transition at fields below 8 T decreases with applied pressure as anticipated, due to loss of free electrons via the Γ–X crossover. However, near 7.5 T, this singlet-like transition exhibits an anomalous branching for pressures above 4 kbar, which indicates the presence of a resonant level and obscures the blue-shift at high fields. 相似文献
943.
G. Fischer E. Dormann 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(1):21-27
High-resolution 13C nuclear magnetic resonance with 1H cross polarization and 1H decoupling under magic angle spinning is measured for the quasi-one dimensional organic conductor diperylene hexafluorophosphate
(including tetrahydrofurane solvent molecules) at temperatures between 160 K and 270 K. Ab initio molecular orbital calculations are used for chemical shift analysis and for assignment of Knight shifted lines and individual
carbon positions. The coexistence of neutral perylene molecules and perylene radicals in the same radical cation salt is revealed.
From Knight and chemical shifts we were able to distinguish two inequivalent perylene radicals within the conducting stack.
The spin density distribution of the molecular electronic wave function is determined quantitatively for these radicals.
Received 29 June 1999 and Received in final form 4 November 1999 相似文献
944.
研究了聚(N,N-二甲基苯胺)在硫酸和三氯醋酸水溶液中的质子化行为,对其吸收光谱和核磁共振谱的研究发现,聚(N,N-二甲基苯胺)在不同酸度下存在两种质子化状态:在强酸体系中质子加在侧基氮原子上,在中等酸性体系中质子加在主链的苯环上. 相似文献
945.
Simple analytical recurrent formulae of the branching rules for group chain SU(2N)⊃(SU(N)⊃O(N)⊃O(3))⊗SU(2) are obtained. The highest weight states for the irreducible representations [2alb] or {nS} of group SU(N) and for the irreducible representations (2α1β) or (υS) of group O(N) are constructed respectively 相似文献
946.
三原子分子振转激发态的理论研究谢代前,鄢国森,田安民(四川大学化学系,成都,610064)关键词振转激发态,三原子分子,变分法能级较高的振转激发态通常包含大振幅运动,其波函数分布于很广的势能面区域内,传统的正则模理论已不适合于解决这类问题.近年来,H... 相似文献
947.
提出了制备压缩相干态的叠加态,亦即类Schrodnger猪态的方案,该方案是基于强度依赖耦合的Jaynes-Cummings模型在远离共振极限下的时间演化而设计的。 相似文献
948.
本文根据量子力学的线性叠加原理,构造了由多模(即q模时目平态的相反态|{{-Zj}〉q及多模虚相干态|{{-Zj}〉q这两者的线性叠加所组成的一种新型的多模Schrodinger猫态光场利用新近建立的多模压缩态理论,研究了态的N次方Y压缩效应,结果发现:①当压缩阶数N=Zp且p=2m(m=1,2,3,…,…)时,态。总是恒处于N-Y最小测不准态;②当压缩阶数N=2p且p=2m+1(m=0,1,2,3,…,…)时,如果各模的初始相位,态间的初始相位差以及各单模相干态光场的平均光子数之总和等满足一定的量子化条件,则态可呈现出周期性变化的、任意阶的N次方Y压缩效应;③当压缩阶数N=2P'+1时,无论p'=2m(m=0,1,2,…,…)还是p'=2m+1(m=0,1,2,3,…,……),只要各模的初始相位满足一定的量子条件,则当两态叠加几率幅满足时,态就恒处于N-Y测不准态,始终不呈现N-Y最小测不准态和N次方Y压缩;而当时,态始终不呈现N-Y测不准态、N-Y最小测不准态和N次方Y压缩效应. 相似文献
949.
M. Sassetti F. Napoli B. Kramer 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(4):643-654
Using the bosonization technique, a theory for the collective excitations of the interacting electrons in quantum wires with
two subbands occupied is developed. The dispersion relations for the inter-subband charge and spin density excitations are
determined. The results are used to interpret the features observed in recent measurements of the Raman spectra of AlGaAs/GaAs
quantum wires, particularly for photon energies near band gap resonance. It is shown that peaks previously identified as “single
particle excitations” are signatures of higher order collective spin density excitations. Predictions about the observability
of the interband modes are made.
Received 8 February 1999 相似文献
950.
A. Ślebarski A. Jezierski M. Neumann S. Plogmann 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(4):519-523
The electronic structure of the Co2-xZrSn Heusler alloys has been studied by X-ray photoelectron spectroscopy (XPS). XPS valence band spectra can be compared with
ab initio electronic structure calculations using the linearized muffin-tin orbital (LMTO) method. The calculated magnetic moments
per Co atom agree well with the moments obtained from experiment. The LMTO calculations also show the energy shifts of the
Co, Zr and Sn valence electron states towards the Fermi level when the concentration of vacancies increases in these alloys.
Received 9 March 1999 and Received in final form 6 May 1999 相似文献