塞曼效应测光速实验中影响精度的因素分析

通常情况下该实验用以对电子的荷质比进行测量。笔者发现,如果进行逆向构思,把电子的荷质比作为已知量时,可重新进行理论推导从而得到真空中的光速值。基于该理论基础重新设计塞曼效应试验,就可以得到测量光速的一种新方法。本文主要就采用这一方法测光速时,对影响测量精度的主要因素进行了分析。     

塞曼效应对正常金属/d波超导结中微分电导的影响

通过外加塞曼磁场在d波超导中,研究磁场对d波超导及其正常金属/d波超导结中隧道谱的影响。研究表明(1)塞曼磁场能使能隙变小,且随着磁场变大,超导态会变为正常态,产生一级相变;(2)塞曼磁场可导致零偏压电导峰劈裂,劈裂宽度为2h0(h0为塞曼能)。     

利用原子的塞曼光谱对半导体激光器进行稳频

中性原子的超精细能级在磁场中产生塞曼分裂 ,另外 ,左旋和右旋圆偏振光激发下原子的跃迁选择定则不同 ,因此 ,原子在超精细塞曼能级间的吸收谱峰相对无磁场条件下的吸收谱峰有一定的移动。利用这一点 ,验证了一种简单、灵活的方法对半导体激光器进行稳频 ,使激光器的线宽稳到小于 1MHz。通过对实验结果的分析 ,发现由左旋和右旋圆偏振光激发引起的原子吸收谱峰移动之和与饱和吸收峰半高宽相等时 ,稳频效果最好     

磁场作用下的有机电致发光

分别制备了荧光器件ITO/NPB/Alq₃/LiF/Al和磷光器件ITO/NPB /CBP: Ir（ppy）₃/BCP/Alq₃/LiF/Al, 测试了50 mT磁场作用下器件的I-V和L-V特性. 与零磁场相比荧光器件和磷光器件的效率分别增加了44%和7%. 从有机电致发光的机制出发对该现象进行了解释, 认为外加磁场可以使三重态激子发生塞曼分裂, 进而在荧光器件中引起了三重态激子T     

外加电场和Al组分对纤锌矿AlGaN/GaN量子阱中的电子g因子的影响

研究了外加电场和垒层的Al组分对AlGaN/GaN量子阱中的横向和纵向g因子(g⊥和g//)及其各向异性(δg)的影响.纤锌矿体结构的贡献(S_//~(bulk)和g⊥)是构成g⊥=(g//-g_0)=g_//~(bulk)的主要部分,但g_//~(bulk)和g⊥的差值很小且几乎不随外加电场和Al组分改变.当外加电场的方向同极化电场的方向相同(相反)且增加时,g_//~(bulk)和g_⊥~(bulk)的强度同时增加(减小).当外加电场从-1.5×10~8 V·m~(-1)到1.5×10~8 V·m~(-1)变化时,异质结界面对g⊥的贡献(Γ_(Inter))大于0且强度缓慢增加,阱层对g⊥的贡献(Γ_W)小于0且强度也缓慢增加.然而Γ_(Inter)的强度比Γ_w大,且后者的强度随着外加电场的改变增加较快,所以δg0且强度随着外加电场的变化而减小.当垒层的Al组分增加时,如果不考虑应变效应(S_(1,2)=0),g_//~(bulk)和g⊥的强度同时减小,然而考虑应变效应后(S_(1,2)≠0),β_1g⊥和γ1(g_//~(bulk))的强度随着Al组分的增加而增加.随着垒层Al组分的增加,Γ_(Inter)和Γ_w的强度都增加,但Γ_(Inter)的强度较大且增加得较快,所以的的强度缓慢增加.g⊥的强度先随着Al组分的增加而减小,然后又随着Al组分的增加而增加,因为g⊥小于0且强度随着Al组分增加得很快.结果表明,AlGaN/GaN量子阱结构中的电子g因子及其各向异性可以被外加电场、垒层的Al组分、应变效应和量子限制效应共同调制.     

The emergence of bound states in a superconducting gap at the topological insulator edge

We consider the edge of a superconducting topological insulator with the impurity in the presence of the Zeeman field. We analytically prove that in the trivial phase two Andreev bound states (ABSs) arise with energies moving from the superconducting gap edges to zero forming two Majorana-like bound states, as the impurity strength varies from 0 to ±2. When the Zeeman field is locally perturbed, ABSs arise both in the trivial and topological phases, but in the topological phase ABSs with energy near the gap edges cannot transform into Majorana bound states and vice versa.     

Quadratic Zeeman corrections for metastable levels of Mg and Ca

Summary The expressions for the corrections to the frequency of the³ P ₂−³ P ₁ and³ P ₁−³ P ₀ π-transitions of Mg and Ca are derived, taking into account the anomalous magnetic moment of the electron as well as the diamagnetic term of the Hamiltonian. Numerical results for²⁴Mg are given.

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Riassunto Si riportano le espressioni analitiche per la correzione di frequenza dovuta all'effetto Zeeman del second'ordine per le transizioni π del tripletto³ P di Mg e Ca. Le correzioni tengono conto del momento magnetico anomalo dell'elettrone e del termine dell'Hamiltoniana responsabile del comportamento diamagnetico dell'atomo. Sono forniti i risultati numerici per il²⁴Mg.

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Резюме Выводятся выражения для поправок к частоте³ P ₂−³ P ₁ и³ P ₁−³ P ₀ π-переходов для Mg и Ca, учитывая аномальный магнитный момент электрона, а также диамагнитный член Гамильтониана. Приводятся численные результаты для²⁴Mg.

     

NQR investigations in crystalline 2,5-dichloroacetanilide

Two close NQR lines were observed in 2,5-dichloroacetanilide at room temperature at 34.606 MHz and 35.212 MHz as well as at liquid nitrogen temperature at 34.832 MHz and 35.791 MHz, using a self-quenched super-regenerative spectrometer. Analysis of the Zeeman effect on the two lines using a cylindrical single crystal reveals that the crystal belongs to either orthorhombic or monoclinic system. There are two crystallographically equivalent but physically non-equivalent directions for the principal field gradientZ axes making an angle of 77° for both resonance lines. The unit cell contains either two or a multiple of two molecules. There is an in-plane bending of the two C-Cl bonds by 1°. The ionic, single bond and double bond characters of C-C1 bonds for both chlorines are almost equal and are in the ratio 25:74:1.     

Investigation of trace level binding of PtCl6 and PtCl4 to alfalfa biomass (Medicago sativa) using Zeeman graphite furnace atomic absorption spectrometry

Batch laboratory experiments were performed to investigate the effects of pH, chemical modification, time dependency, and interference studies on the binding of trace concentrations of hexachloroplatinate(IV) and tetrachloroplatinate(II) to alfalfa biomass. The pH profiles were measured between pH 2.0 and 6.0. It was found that the binding of trace concentrations of platinum(IV and II) to alfalfa biomass was dependent on pH with a maximum binding occurring at pH 3.0 and a minimum at pH 6.0. When the alfalfa biomass was chemically modified (esterified), maximum binding occurred at pH 6.0 for both oxidation states of platinum. From the batch time dependency experiments, it was found that binding took at least 20 min to level off for both platinum oxidation states. Batch experiments were performed with various concentrations of calcium, magnesium, and sodium (0.1, 1.0, 10, 100 and 1000 ppm) and it was found that calcium affected the binding of platinum(II and IV) to the alfalfa biomass. It was determined that magnesium and sodium did not interfere appreciably with the binding of platinum in either of the oxidation states studied. Finally, batch experiments were performed with Mg²⁺, Ca²⁺ and Na⁺ in solutions at various concentrations, and it was observed that the binding was affected similarly to that by calcium alone.