Na原子能量自囚禁的加速效应

采用高分辨激光光谱方法，在较高温度条件下，实验观察到Na原子能量自囚禁加剧特征。出现原子加速的光谱行为；并导致零速度原子碰撞转移到高激发态的速度减少。从原子内能碰撞转移的角度，分析了原子速度分布变异的机理。     

产生于能量积聚效应的钠原子高激发态碰撞转移速率的功率效应

报道了用连续单模激光器将Na原子共振激发至3P态,观察到通过Na(3P)-Na(3P)能量积聚碰撞过程布居的高激发态荧光随激发光功率的变化关系。根据碰撞转移模型运用近似二能级系统下的速率方程对实验结果作了解释,理论分析与实验数据相结合得到了高激发态的碰撞转移速率k4D,k5P,k4P,k5S随激发光功率增长的变化特性。     

Rb（5PJ）＋Rb（5PJ）→Rb（5JS）＋Rb（nl=5D，7S）碰撞能量合并

研究了Rb(5PJ)+Rb(5PJ)→Rb(nlJ')+Rb(5S)碰撞能量合并过程,利用单模半导体激光器分别共振激发Rb原子的5P1/2或5P3/2态,利用另一与泵浦激光束反向平行的单模激光束作为吸收线探测激发态原子密度及其空间分布,吸收线分别调至5P1/2→5D3/2和5P3/2→7S1/2跃迁.由激发态原子密度和谱线荧光比得到碰撞能量合并过程的截面,对5P3/2激发,碰撞转移得到5D5/2,5D3/2和7S1/2的截面分别是(1.32士0.59)×10-14,(1.18士0.53)×10-14和(3.21士1.44)×10-15cm2;对5P1/2激发,碰撞转移到5D5/2和5D3/2的截面分别是(6.57士2.96)×10-15和(5.90士2.66)×10-15cm2.与其他的实验结果进行了比较.     

Rb(5PJ)+Rb(5PJ)→Rb(5S)+Rb(nl=5D,7S)碰撞能量合并

研究了Rb(5PJ) Rb(5PJ)→Rb(nlJ') Rb(5S)碰撞能量合并过程,利用单模半导体激光器分别共振激发Rb原子的5P1/2或5P3/2态,利用另一与泵浦激光束反向平行的单模激光束作为吸收线探测激发态原子密度及其空间分布,吸收线分别调至5P1/2→5D3/2和5P3/2→7S1/2跃迁.由激发态原子密度和谱线荧光比得到碰撞能量合并过程的截面,对5P3/2激发,碰撞转移得到5D5/2,5D3/2和7S1/2的截面分别是(1.32士0.59)×10-14,(1.18士0.53)×10-14和(3.21士1.44)×10-15cm2;对5P1/2激发,碰撞转移到5D5/2和5D3/2的截面分别是(6.57士2.96)×10-15和(5.90士2.66)×10-15cm2.与其他的实验结果进行了比较.     

高激发态原子间的范德瓦尔斯相互作用

与基态原子相比,高激发态原子(主量子数n15)具有很强的长程范德瓦尔斯(Van der Waals)相互作用,这种强相互作用可以阻止相邻原子的进一步激发,产生激发阻塞效应.本文从理论上利用微扰方法计算碱金属原子Rb和Cs激发态nS,nD原子对态的相互作用,获得原子相互作用的色散系数并分析了原子间的长程相互作用特性.结果表明,Rb和Cs原子的nS态表现为排斥相互作用,而nD态原子L=0时,Rb原子表现为吸引作用,Cs原子表现为排斥作用.     

双光子共振激发Rb原子高激发态的瞬态相干效应

本文采用微微秒同步泵浦可调谐染料激光器,研究了Rb原子高激发态15d的双光子共振激发和增强效应,获得了1.065μ→4210(?)的频率上转换;给出自位相匹配与4210(?)相干辐射输出的关系.本文重点研究了高激发态的瞬态相干效应,得到了高激发态瞬态相干的失相过程;实验指明,双光子共振激发获得最大极化的时间是120ps,直到350ps,在探测光作用下仍可诱导出4212(?)相干辐射光.     

Rb蒸气中的5PJ+5PJ′→5S+5DJ″碰撞能量合并

研究了Rb(5PJ) Rb(5PJ′)→Rb(5S) Rb(5DJ″)的碰撞能量合并过程,一台单模半导体激光器共振激发Rb原子的5P1/2或5P3/2态,另一与泵浦激光束反向平行的单模激光束作为吸收线探测激发态原子密度及其空间分布,吸收线分别调至5P1/2→5D3/2和5P3/2→7S1/2跃迁,由激发态原子密度和谱线荧光比得到碰撞能量合并过程5PJ 5PJ′→5S 5DJ″的截面.两台激光器同时分别激发5P1/2和5P3/2态,通过对5DJ″→5PJ的荧光探测,得到5P3/2 5P1/2碰撞转移到5D5/2和5D3/2的截面分别为(1.12±0.50)×10-14和(1.01±0.45)×10-14cm2.     

钠原子第一激发态的非共振发射谱

一、引 言 这里的非共振发射谱是来源于碰撞引起的激发态精细结构之间的能量转移.对Na的第一激发态就是 Na(32P3/2)+X 　 Na(32P1/2)+X+　E(1)其中X是具有一定动能的碰撞原子,△E是3P态精细结构分裂能量。 精细结构之间的能量转移过程的研究不仅对于了解原子之间相互作用的机制有重要作用,而且很有实际意义.例如,最近Gelhwachs等人[1]把饱和光学非共振发射谱用于Na的单原子检测得到了相当好的结果. 我们利用Ar+激光泵浦的连续染料激光器对Na原子的D1,D2线分别进行选择性激发.观察了共振及非共振荧光.研究了它们随激发光强、Na原子密…     

钡原子高激发态吸收谱的研究

一、引言高激发态原子是在外壳电子受到激发后处于主量子数 n 很大状态的原子,亦称为Rydberg 原子.这些原子具有玻尔半径大,能级寿命长,束缚能小等特点.开展对高激发态原子的研究对研究激光与     

Rb(5P)激发态的辐射及与N2碰撞的能量转移

应用激光吸收和荧光方法,测量了Rb(5P)态与N2碰撞的精细结构混合和碰撞猝灭截面.Rb原子被激光激发到5P3/2态,将与泵浦激光束反向平行的检测激光束调到5PJ→7S1/2的跃迁,测量5PJ激发态的密度及空间分布,由此计算了5PJ→5S的有效辐射率,在T=340K和N2密度0.5×1016＜N＜4×1016cm-3范围内测量了5P1/2→5S1/2(794nm)发射的敏化荧光强度I794,量N/I794与N有抛物线型的关系,表明了5PJ的猝灭是由于与N2分子的碰撞产生的,而不是由与Rb基态原子碰撞产生的.由最小二乘法确定的二次多项式的系数得到5P态与N2碰撞精细结构混合截面σ3/2→1/2=(10.43±3.54)×10-16cm2,猝灭截面σD=(9.8±3.4)×10-16cm2.与在不同的实验条件下得到的结果在误差范围内一致.     

Isotope separation of Dy atoms using laser excitation followed by charge exchange with Cs+ ions

Dysprosium atoms were isotope selectively excited by cw dye laser light. They were ionized by charge transfer collisions with Cs⁺ ions. The process was found to discriminate well between ground state and excited state atoms. The cross section ration for the two competing processes was determined to be about 10³.     

Experimental investigation of ultracold atom-molecule collisions

Ultracold collisions between Cs atoms and Cs2 dimers in the electronic ground state are observed in an optically trapped gas of atoms and molecules. The Cs2 molecules are formed in the triplet ground state by cw photoassociation through the outer well of the 0-(g) (P3/2) excited electronic state. Inelastic atom-molecule collisions converting internal excitation into kinetic energy lead to a loss of Cs2 molecules from the dipole trap. Rate coefficients are determined for collisions involving Cs atoms in either the F=3 or F=4 hyperfine ground state, and Cs2 molecules in either highly vibrationally excited states (nu'=32-47) or in low vibrational states (nu'=4-6) of the a3 summation(u)+ triplet ground state. The rate coefficients beta approximately 10(-10) cm3/s are found to be largely independent of the vibrational and rotational excitation indicating unitary limited cross sections.     

Role of atomic inelastic collisions in a Cs-He steady state discharge

The population of various excited states and the electron temperature in a mixture of cesium vapor and helium have been measured spectroscopically in a stationary electrical discharge where helium atoms remain in their ground state. An equilibrium between the populations of highly excited cesium levels was observed to be characterized by a Boltzmann temperature equal to the gas temperature. It is concluded that the populations of these high levels are more influenced by Cs¹+He inelastic collisions than by Cs¹+e collisions when [He]/[e]?10⁶. The influence of the helium atoms has also been observed on the relation between electron temperature and electron density.     

Cs蒸气中的碰撞能量合并和6P3/2和6P1/2间的激发转移

通过激发转移和碰撞能量合并研究了Cs(62P)精细结构混合.单模半导体激光器激发基态Cs原子至6P3/2态,直接荧光是由6P3/2态发射的,敏化荧光是由精细结构碰撞转移和碰撞能量合并产生的.由相对荧光强度得到了转移截面σ(6P3/2→6P1/2)=(1.5±0.5)×10-15cm2,与其它实验结果进行了比较.     

Lifetime-measurements of alkali-molecules excited by different laserlines

Absorbing different lines of acw-argon ion laser or a He-Ne-laser the alkali molecules Na₂, K₂, Rb₂ and Cs₂ can be pumped into different rotational-vibrational levels of an excited electronic state. The lifetimes of these states have been measured using the phase shift technique at a modulation frequency of 18 Mc/sec. Because of collisions with the always present alkali atoms the excited molecules may undergo collision-induced transitions to other states and their lifetimes are dependent on the atomic pressure. This dependence was measured and the spontaneous lifetimes were obtained by extrapolation against zero pressure. Different collision processes are discussed which compete with the unperturbed fluorescence.     

Inverse hook method for measuring oscillator strengths for transitions between excited atomic states [1]

We describe an effective new method to measure the oscillator strengths for transitions between the excited states of atoms. The oscillator strength is determined, by measuring changes in the angular distribution or polarization of fluorescence light emitted by atoms in the initial or final state of the transition of interest, after these atoms have been subject to the a.c. Stark shift of an off-resonant laser pulse. The physics of the situation is very similar to that of the conventional hook method with this difference: the roles of the atoms and the photons have been interchanged. We therefore call this new methodthe inverse hook method. The inverse hook method is relatively insensitive to the details of the atomic absorption lineshape and also to the temporal and spectral profile of the laser pulse. It yields absolute oscillator strengths and it is especially suitable for measurements of transitions between excited atomic states, including autoionizing states.     

激光诱导镁原子S—S,S—D禁戒跃迁

报道在镁金属蒸气中利用两束激光三光子共振激发原子３ｓｎｐ１Ｐ中高里德堡态时，观察到随泵浦激光功率的增强，出现３ｓ４ｓ１Ｓ０－３ｓｎｓ１Ｓ０、３ｓｎｄ１Ｄ２（ｎ≈１８～３２）偶宇称态偶极禁戒跃迁增强，以及３ｓｎｓ１Ｓ０能级移动现象，并解释为光泵过程引起的原子激发态碰撞效应。利用禁戒跃迁首次测定了Ｍｇ３ｓｎｓ１Ｓ０（ｎ＝２２～３０）能级。     

Infrared laser-emission study in a resonantly excited sodium vapor

We report on a study of time dependence of ir laser emission at 3.41 μm in a dense Na vapor that is resonantly excited to the 3² P levels by a flashlamp, pumped dye laser. Energy-pooling collisions (excitation transfer) between excited atoms create a large population inversion among the 5² S _1/2 and 4² P _3/2 states which is destroyed by electron collisions as a result of subsequent plasma formation. The ir laser emission may serve as a new diagnostic tool to follow the time evolution of such media.     

磁光阱中超冷钠-铯原子碰撞的实验研究

研究了磁光阱中异核超冷钠铯原子的碰撞机理, 测量了超冷钠原子的碰撞损失率, 得到了钠-铯原子的碰撞损失系数β_Na-Cs与钠原子俘获光强度之间的关系. 利用多普勒模型计算了不同俘获光强度下的钠原子磁光阱的阱深, 得到了临界光强的理论值, 与实验结果符合得较好.     

On the excitation mechanism of the He-Ar hollow cathode laser

Investigations were carried out on the Ar-II 476.5 nm laser to obtain information on possible excitation mechanisms. The He-Ar hollow cathode discharge was excited by square wave current pulses. From the results of measurements it could be concluded that collisions of the second kind between He 2³ S metastable atoms and ground state Ar ions are dominant in the excitation of the upper laser level. This is also supported by results obtained in the case of the He-Kr hollow cathode laser, where the upper level of the Kr-II 469.4 nm laser is excited by a similar collision process.