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采用密度泛函B3LYP(Becke,three-parameter,Lee-Yang-PaH)/6-311++G**和HF(Hartree Fock)/6-311++G**方法,从理论上探讨了2-F-环氧丁烷分别与几种常见而重要的生物小分子咪唑(Iminazole)、噻唑(Thiazole)和恶唑(Oxazo1e)等分子间的弱相互作用,发现分子间同时存在N…H常规氢键和C-F…H-C赝氢键结构.弱相互作用能计算表明3个复合物的相对稳定性相当.计算结果表明,在C-F…H-C赝氢键结构中,与电子的直接供体F密切相关的共价键C-F键长增大,伸缩振动的频率红移,而作为电子受体的H-C基团,其C-H键伸缩振动光谱蓝移;另外,电子密度拓扑性质表明C-F…H-C赝氢键的共价性及离子性均与常规氢键相当. 相似文献
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On the basis of relativistic ab initio calculations, we show that both Te- and I-terminated surfaces of the polar layered semiconductor BiTeI hold surface states with a giant Rashba-type spin splitting. The Te-terminated surface state has nearly isotropic free-electron-like dispersion with a positive effective mass, which along with the giant spin splitting makes BiTeI fulfilling the requirements demanded by many semiconductor-spintronics applications. The I-terminated surface state with its negative effective-mass dispersion reproduces nicely the situation with the Rashba-split surface state on surfaces of noble-metal based surface alloys. The crucial advantage of BiTeI as compared with the surface alloys is the location of the I-terminated surface state in a quite wide band gap. 相似文献
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R. Chulkov V. Lisinetskii O. Lux H. Rhee S. Schrader H. J. Eichler V. Orlovich 《Applied physics. B, Lasers and optics》2012,106(4):867-875
Raman frequency conversion of high average power pulsed Nd:YAG laser radiation into the near IR spectral region in a barium
nitrate Raman laser was studied with the emphasis on thermal effects inside the Raman-active medium. The probe-beam technique
together with numerical reconstruction, done by integrating the transient heat conduction and paraxial wave equations, revealed
dynamics of the induced distortions featuring high-order optical aberrations. By utilizing the Zernike expansion of the reconstructed
phase profile and implementing a special focusing geometry of the pump beam, partial compensation of the distortions was realized
in a stable configuration of the Raman cavity. Generation of the first-, second-, and third-order Stokes radiation with output
power of 17, 9.5, and 5.5 W corresponding to a quantum conversion efficiency of 32, 21, and 13% is reported. 相似文献
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Evolution from Diffuse Ferroelectric to Relaxor Ferroelectric in Pb1-xBax(Fe1/2Nb1/2)O3 Solid Solutions 下载免费PDF全文
Dielectric and ferroelectric characteristics for Pb1-xBax(Fe1/2Nh/2)O3 (x = 0,0.05,0.1,0.15, and 0.2) ceramics are determined together with their structures. X-ray diffraction (XRD) analysis confirms the solid solutions with the cubic structure. The dielectric nature changes from diffuse ferroelectric to relaxor ferroelectric with increasing x, while the phase transition temperature Tc (or Tm) decreases monotonously. The diffuse ferroelectric phase transition is observed in the solid solutions with 0≤x ≤0.05. For Pbl-xBax(Fe1/2Nb1/2)O3 with 0.1≤ x≤0.2, relaxor ferroelectric behavior is determined, and the Vogel-Fulcher equation is used to describe the relaxor behavior. The 1/ε versus T plots reveal the diffusion dielectric characteristics in both diffuse and relaxor ferroelectrics. 相似文献
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Yu. S. Ponosov T. V. Kuznetsova O. E. Tereshchenko K. A. Kokh E. V. Chulkov 《JETP Letters》2014,98(9):557-561
Raman measurements of the phonon spectrum of BiTeI at pressures of up to 20 GPa have been performed. A decrease in the linewidth of E2 vibration by almost a factor of 2 with an increase in the pressure to 3 GPa has been detected. The frequencies of all four Raman active modes increase monotonically with the pressure. These lines are observed in spectra up to ~8 GPa. Sharp change in the spectrum occurs at pressures of 8–9 GPa, indicating a transition to the high-pressure phase, which holds up to 20 GPa. This transition is reversible and hardly has any hysteresis. A sample in the high-pressure phase is single crystal. 相似文献