Atom Microscopy via Dual Resonant Superposition

An M-type Rb⁸⁷ atomic system is proposed for one-dimensional atom microscopy under the condition of Electromagnetically Induced Transparency. Super-localization of the atom in the absorption spectrum while its delocalization in the dispersion spectrum is observed due to the dual superposition effect of the resonant fields. The observed minimum uncertainty peaks will find important applications in Laser cooling, creating focused atom beams, atom nanolithography, and in measurement of the center-of-mass wave function of moving atoms.     

Observation of the vacuum Rabi spectrum for one trapped atom

The transmission spectrum for one atom strongly coupled to the field of a high finesse optical resonator is observed to exhibit a clearly resolved vacuum Rabi splitting characteristic of the normal modes in the eigenvalue spectrum of the atom-cavity system. A new Raman scheme for cooling atomic motion along the cavity axis enables a complete spectrum to be recorded for an individual atom trapped within the cavity mode, in contrast to all previous measurements in cavity QED that have required averaging over 10(3)-10(5) atoms.     

脉冲形状对氢原子高次谐波的影响

在含时密度泛函理论框架下,采用经典和量子相结合的模型,模拟了氢原子在超强飞秒激光脉冲作用下的高次谐波产生现象,并研究了激光脉冲形状对氢原子高次谐波的影响.结果表明,氢原子的高次谐波谱具有典型的原子谐波谱的特征;具有“下降－平台－截止”的结构和偶次谐波被禁闭仅出现奇次谐波的选择性特征;不同的脉冲形状会导致高次谐波的截止频率和谱线强度的变化.     

Cd(II) line spectrum emission from semiconductive CdS single crystals

A new method of atom or ion excitation is demonstrated using a semiconductive CdS single crystal. The intense light emission of Cd(II) ion is observed at an adequate He gas pressure, in addition to the Cd(I) atomic line spectrum, when the comparatively low pulse voltage of 810 V/cm is applied to the CdS single crystal. The excitation of Cd(II) is the result of the Penning effect and the energy exchange between He⁺ and Cd atom. Also, the line spectrum emissions of Tl, Ca, Ba, Al, and Ag, which are evaporated on the CdS single crystal, can be observed under the pulse voltage. Our excitation method for the ion or neutral atom is unique in that it requires a comparatively low field for operation and no additional heater for thermal vaporization of those elements.     

Superposition of Stationary Wave Fields Via Atom Microscopy

We investigate one-dimensional position microscopy of a three-level atom moving through a stationary wave region under the condition of electromagnetically induced transparency.The precise position information of an atom is observed on the resonance absorption and dispersion distribution spectrum of a weak probe field.Single and multiple localization peaks are observed in specific directions of the corresponding wave numbers and phase of the standing wave fields.The strength of space-independent Rabi frequency reduces the position uncertainty in the localized peaks without disturbing the probability of the atom.In a hot atomic medium the localized probability of an atom is reduced which depends upon the temperature of that medium.Our results provide useful applications in the development of laser cooling,atom nanolithography and Bose-Einstein condensation.     

二能级原子与高品质因子腔的自发辐射特性

用全量子理论研究二能级原子单模腔耦合系统,通过理论推导和数值计算得出系统的自发辐射光谱和平均粒子数密度.共振时腔与原子的发射光谱在强耦合与弱耦合区域有所不同,腔发射光谱分裂只出现于强耦合区域,而原子发射光谱由于腔感应透明效应在弱耦合区域出现了缺口.本文系统地研究了原子与腔在失谐时的发射光谱,在好腔机理(腔线宽小于原子线宽g)原子与腔即使在大失谐时腔发射出腔频率的光子,这给当前实验上困惑的特性提供了一个理论依据.为了给腔感应透明效应一个新的深入了解,还研究了原子与腔平均粒子数密度随时间的演化,以及平均粒子数密度与光强度之间的关系. 关键词： 自发辐射 强耦合 腔感应透明 好腔机理     

压制压力对La_(0.7)Sr_(0.3)MnO_3纳米固体内部氧的状态的影响

本文测量了Ｌａ０．７Ｓｒ０．３ＭｎＯ３纳米固体的Ｘ射线光电子能谱,观察到高压对氧原子状态的影响。     

Sub-half-wavelength atom localization via probe absorption spectrum in a four-level atomic system

We present a simple scheme of atom localization in a subwavelength domain via manipulation of probe absorption spectrum in a four-level atomic system. By applying two orthogonal standing-wave fields, the localization peak position and number as well as the conditional position probability can be controlled by the intensities and detunings of optical fields, and the sub-half-wavelength atom localization is also observed. More importantly, there is 100% detecting probability of the atom in the subwavelength domain when the corresponding conditions are satisfied.     

Atomic and electronic structure of the Si(001) surface induced by hydrogen-adsorption

The initial stage of hydrogen (H) adsorption on the Si(001) surface is theoretically investigated to clarify the atomic and electronic structure induced by the adsorption. For this purpose, the electronic states are calculated in the density functional approach with the DV(discretized variation)-Xα-LCAO method. We also simulate the scanning tunneling microscopy (STM) image and the scanning tunneling spectroscopy (STS) spectrum in the first-principles approach. Our results of the STM image do not support the asymmetric dimer structure of the substrate with a H atom bonded to the upper Si atom. They conclude that the bright ball-like spot in the observed images comes from the free dangling bond induced on the remaining Si atom of the reacted dimer. However, the single particle picture cannot reproduce the observed features of the STS spectrum at the spot. We discuss that all the features can be well explained by the Coulomb blockade effect due to the electron correlation in the dangling bond state.     

Fe-Ni殷钢的穆斯堡尔谱研究

用穆斯堡尔谱研究了Fe-Ni殷钢的磁性特征,证实合金中存在两种不同磁态的Fe原子,并依此解释了殷钢效应。提出了测定合金中两种状态Fe原子磁矩的公式。报道了Fe-Ni合金在Ni32wt%附近的一些反常现象。 关键词：     

与氢原子有关的原子光谱跃迁问题

本文以氢原子为例,阐述了玻尔的氢原子理论及引入相对论效应及量子理论后氢原子光谱的精细结构和超精细结构。同时,进一步在理论上深入探讨谱线精细结构、跃迁概率、谱线轮廓、谱线强度对原子光谱跃迁的影响,更深入地理解了原子光谱跃迁问题。     

Modification of the resonance fluorescence spectrum of a two-level atom in the near field of a plasmonic nanoparticle

The resonance fluorescence spectrum of an atom located in the near field of a plasmonic nanoparticle is considered. It is shown that, as the atom gets close to the nanoparticle, the high-frequency peak of the Mollow triplet disappears and the spectrum has a Fano resonance shape. The low-frequency peak also disappears as the distance between the atom and the nanoparticle decreases further. For small distances, when the atom interacts with the nanoparticle much more strongly than with the external field, the spectrum represents a Lorentzian line whose width is proportional to the square of the atom-nanoparticle coupling constant.     

氢原子的X射线新谱系的实验观测及其解释

 引出氢（氘）气放电产生的射线和粒子流打在非晶聚氘乙烯C₂D₄和有机玻璃C₅H₈O₂等靶上,测得其散射谱上有多条尖锐的X谱线,其中除一条外都是（不经散射的）原始谱中没有的。经反复证认,这些谱线不是靶中元素（如C或O）和可能包含的杂质元素的特征X射线,也不是原始谱中X射线的衍射线,更不可能是低能电子的轫致辐射经吸收后形成的峰,认为该谱线很可能是前所未知的一类新的原子态的X射线新谱系的一部分。用曾提出的一个“小氢原子”理论模型予以解释,即认为氢（氘）气放电中产生了“小氢原子”,其（在基态）电子轨道半径约为普通氢原子的玻尔半径的1/274,该小氢原子能级之间的跃迁能够很好地解释所测到的X射线新谱系。     

Manipulation of inherent characteristics of graphene through N and Mg atom co-doping; a DFT study

First-principles calculations were performed to investigate the structural, electronic, magnetic and optical properties of nitrogen (N) and magnesium (Mg) atom co-doped graphene systems. We observed that, N and Mg atom co-doping in graphene, introduces half-metallic properties in the electronic structure of graphene, introduces ferromagnetism behavior along with new trends in optical properties of graphene. Doping site and concentration of N and Mg atoms in graphene was changed and resulting effects of these changes on aforementioned properties were investigated. Through density of states plots we observed that, Mg atom sp orbitals mainly induced magnetic moments in graphene. It was revealed that, N/Mg atoms substitution in graphene introduces a red shift in absorption spectrum towards visible range and a finite absorption coefficient quantity value in 0 to 3 eV and 7 to 11 eV energy intervals is also produced, that is unavailable for absorption spectrum of intrinsic graphene. Moreover, N/Mg atoms co-doping produces increment in the reflectivity parameter of graphene in low lying energy region, while producing diminishing behavior in the higher energy range. These results offer a possibility to tune electronic, magnetic and optical characteristics of graphene sufficiently for utilization in graphene based spintronic and optoelectronic devices.     

Geometric Phase and Sidebands

Geometric phase of mixed state is expanded for a two-level atom interacting with a quantized field mode, where master equation is a modified Bloch equation with constant terms that are used to explain emergence of sidebands in the spectrum of the fluorescent light. The results show that geometric phase transition is observed for medium initial angle when the Rabi frequency associated with the driving field becomes comparable to the spectral width of the atom. We find that the geometric phase transition depends on population inversion and Bloch radius, which is helpful to understand mechanism of sideband.     

镓铟磷三元化合物中的自由激子和杂质N发光中心的结构位形

我们研究了GaxIn1-xP:N(x=0.99,0.98,0.96)的发光光谱,用Ar+离子激光器的458nm线激发。N的浓度为5×1017cm-3。图1示出了在6K下Ga0.99In0.01P:N的发光光谱。Mariette和Chevallier[1,2]以及Nelson和Holonyak,Jr[3]。认为Nx0带起源于束缚在孤立N中心上激子的辐射复合。     

Λ-型三能级单原子的辐射谱

采用时间演化算符方法，研究腔内单模光场中Λ－型三能级单原子的辐射谱，给出了辐射谱一般公式，并讨论在粒子数纯态、相干态和热辐射三种光场激励下的辐射频谱结构。     

Auto-and cross-correlation functions of a one-atom laser in a regime of strong coupling

The spectral properties of an incoherently pumped one-atom laser operating in a regime of strong coupling are studied. The spectrum of the field outgoing from the cavity, the spectrum of resonance fluorescence of an atom, and the spectrum of the atom—field cross-correlation function are numerically calculated. Relations between the parameters of the system for which spectral lines corresponding to eigenstates of the Jaynes—Cummings Hamiltonian are resolved are found. A method for determining the widths of resonances from the spectrum of the atom—field cross-correlation function is proposed, and a procedure for measuring this function using spectroscopy of intensity fluctuations is described.     

Polarization bremsstrahlung of heavy charged particles in a polycrystal

Polarization bremsstrahlung (PBS) of a fast ion scattered in a polycrystalline medium is calculated and analyzed with allowance for the contributions from the coherent and incoherent channels of the process. It is shown that scattering of a projectile from the crystal lattice of the target is responsible for typical features of the PBS spectrum. For example, PBS is suppressed (as compared to radiation emitted by a single atom) in the low-frequency part of the spectrum, where coherent PBS dominates. In the intermediate spectral region, a step structure is formed as a result of “elimination” of the contribution from the reciprocal lattice vector with a preset magnitude to the coherent component of the process. Finally, incoherent PBS dominates in the high-frequency part of the spectrum and the process occurs as in the case of a single atom. These spectral peculiarities of PBS are determined by the structure of the target and depend on the velocity of the projectile and the emission angle, and can be observed in experiments dealing with radiation emitted by fast charged particles in thin polycrystalline films.     

Probing the natural broadening of hydrogen atom spectrum based on the minimal length uncertainty

The natural broadening of hydrogen atom spectrum based on the minimal length uncertainty is calculated. We will show that the natural broadening of hydrogen atom spectrum receives any correction.