Sm原子的偶宇称高激发态的光谱研究

采用双色三步激发和光电离过程,对Sm原子的偶宇称高激发态的光谱进行了研究.先采用两条激发路线分别将Sm原子两步共振激发至待测的高激发态,然后利用光电离技术对其进行探测.分别将第一束激光的波长固定在627.50nm和624.41nm上,以便将Sm原子从亚稳态共振激发到由4f⁶6s6p电子组态所构成的两个原子状态上.第二束激光在440-700nm的波段范围内扫描,不仅使Sm原子在30040-38065cm^-1能域内的偶宇称高激发态上布居,将其进一步光电离,测量了其光谱.通过光谱定标和选择定则等分析手段,本工作不仅精确获得了136个态的能级位置,而且也唯一确定了其总角动量,并且给出了相关跃迁的相对谱线强度.     

用双光子电离探测技术研究奇宇称的Sm原子光谱

采用两台激光器对Sm原子奇宇称激发态的光谱及其特性进行了系统研究.利用一台波长在585 nm到663 nm之间调谐的染料激光器,将Sm原子从某个4f⁶6s²⁷F_J(J=0—6)态激发到具有奇宇称的4f⁶6s6p或4f⁵5d6s²激发态.然后,采用波长固定在532 nm的强激光束,对处于上述奇宇称激发态的Sm原子进行双光子电离,以实现探测其光谱信息 关键词： 双光子电离 奇宇称态 Sm原子     

Sm原子奇宇称Rydberg态光谱

结合共振激发和场电离探测技术,通过总角动量量子数0→1→0→1的激发路径,研究了第一电离阈附近的Sm原子奇宇称Rydberg态4f~66snp(J=1)。首先,在45 200～45 500 cm~(-1)能量范围内共发现了94个奇宇称Rydberg能级。其次,通过对有效量子数和Rydberg能级结构特点的分析,将其中68个能级归属为3个束缚Rydberg系列,另外26个能级也给出了能级位置。然后,利用Rydberg-Ritz公式,对3个Rydberg系列分别进行了拟合,获得了Sm原子的电离阈为(45 519.61±0.79) cm~(-1)。最后,采用6种偏振组合激发,由偏振选择定则,进一步验证了这些奇宇称Rydberg态总角动量量子数为1。这些结果首次证实了场电离探测技术对Sm原子高激发Rydberg态的适用性,并且通过对奇宇称Rydberg系列拟合得到的Sm原子电离阈与文献中通过偶宇称Rydberg系列获得的值(45 519.64±1.39) cm~(-1)基本一致。     

铅原子6p7s—6p^2多重态谱线

原子内部各种相互作用决定原子能级,能级结构决定其原子光谱。本文以铅原子6p7s—6p~2跃迁所辐射的多重态谱线为例,计算各能级,分析电、磁性作用强弱。原理铅原子Z=82,基态电子组态[Xe]4f~(14)5d~(10)6s~26p~2,简记6p~2,基本属于LS耦合类型,该电子组态耦合各支能级(谱项),近似地遵循。     

用速度影像技术研究Eu原子6p_(1/2)8s的自电离衰变的分支比

本文采用速度影像技术对Eu原子的自电离弹射电子的动力学过程进行了系统研究.实验采用三步孤立实激发方法分步从基态4f76s6s8S7/2经中间态4f76s6p6P5/2激发到4f76s8s8P7/2Rydberg态上,然后将其进一步共振激发至4f76p1/2(J=3)8s和4f76p1/2(J=4)8s自电离态.根据所用的激发路径及其选择定则可以得出自电离态的总角动量的可能取值;通过自电离过程能量守恒和角动量守恒原理推测自电离衰变对应的离子终态信息.利用电子透镜对上述自电离过程中产生的弹射电子进行聚焦和成像,通过位置敏感探测器对其动能进行分辨,运用速度影像技术进行数学变换和计算得到弹射电子的能量分布,分析并给出Eu原子自电离衰变分支比.同时通过调谐第三步激光的波长,得出了分支比随光子能量的变化规律,探讨了实现Eu离子粒子数反转的可能性.     

利用自电离探测技术研究Sm原子Rydberg态光谱

采用孤立实激发与自电离探测技术相结合的方法对Sm原子偶宇称高激发态进行了系统研究.按照不同的自电离通道将所测数据进行了分类和比较,并进行了详细讨论.不仅报道了许多收敛于不同电离限的Rydberg态的能级位置和跃迁的相对强度等信息,而且还把处于同一能域内的Rydberg态和价态进行了辨识.另外,不但提供了一种有效识别不同类型的高激发态的鉴别技术,而且还对处于41800 cm^-1到43800 cm^-1能域内的Rydberg态和价态的光谱特性进行了详细分析和讨论. 关键词： 自电离探测 Rydberg态 Sm原子     

L-S耦合中原子基态诸量子数的计算

由原子基态的电子组态所形成的可能状态中,能级最低的为原子的基态.在LS耦合中,利用原子中电子的壳层分布,应用洪特定则,可以推导出几个公式计算各种原子基态的总轨道角动量量子数L、总自旋角动量量子数S和总角动量量子数J.一、原子基态(L,S,J)的计算 大多数元素的原子中只有一个次壳层未被电子占满,计算时只需计及这一个次壳层中的电子,其他已占满的次壳层无需考虑.下面先讨论这种情形. 根据洪特定则,由同一电子组态所形成的原子状态中,S最大的态能级最低;具有相同S的态中,L最大的态能级最低.所以,由原子基态电子组态所形成的状态中,S…     

用Schaefer和Harris方法计算LS耦合原子态及其简洁本征函数

应用推广Schaefer和Harris的方法(即对于给定的电子组态,在Slater行列式基上构造算符L2+λS2的矩阵,通过对角化此矩阵求得LS耦合原子态的本征函数)开发一套Fortran程序,不仅可以求得某一对称下最简洁的的LS本征函数,而且能够求得任一电子组态(同科电子组态和非同科电子组态)的所有LS耦合原子态.作为例子,具体计算Np(Z=93)电子组态5f46d的LS耦合原子态和对应于6I光谱项的最简洁的LS本征函数.     

Eu原子4f~76p_(3/2)ns自电离态的光谱的研究(英文)

采用孤立实激发技术,对铕原子4f~76p_(3/2)ns(n=7,8)自电离态的光谱进行了系统的研究,同时是首次在不同激光偏振组合下进行的研究。首先,用前两束激光分步将铕原子从基态4f~76s~2经中间4f~76s6p态激发至4f~76sns里德堡态,然后再用第三束激光通过离子实4f~76s~+→4f~76p~+_(3/2)的跃迁将其进一步激发至4f~76p_(3/2)7s自电离态或4f~76p_(3/2)8s自电离态。对铕原子4f~76p_(3/2)ns(n=7,8)自电离态复杂的光谱分别给出了详细的解释,从中我们可以获得一些重要的光谱信息,比如自电峰的能级位置和线宽等,同时还可以观察到收敛于不同离子限的自电离系列之间的组态相互作用。最后,通过比较不同激光偏振组合下的自电离光谱,确定了一些自电离态的总角动量的值。     

对元素基态电子组态表中几个“特殊”组态的解释

在Pauli不相容原理和能量最低原理的限制下,处于基态时原子中的电子按照 1s,2s,2 p, 3s,3 p,4 s,3d,4p,5s,4d,5p,6s,4f,5d,6p,7s,5f,6d的次序[1]填充,得出原子基态时的电子组态.但是,在元素基态电子组态表[2]中,有十九个“例外”,形成“特殊”的电子组态.其原因需要研究影响ns,(n—1)d,(n—2)f壳层能量的因素《特别是n很大时》. 量子力学中,作为中心力场近似的 Hartree-Fork自洽场方法,给出了多电子原子的能量公式[3] 式中,第一项是单电子原子实的能量(忽略了与所有其他别的电子的相互作用);第二项是两电子相互作用的库仑能,它表示电子密…     

Studies on odd-parity states of the Sm atom

Two-step excitation and ionization processes are used to detect Sm atoms in many excited states populated with tunable lasers. The wavelength of the first laser is tuned to the resonances from the Sm 4f^6 6s^2 ^7FJ （J=0 6） states to many odd-parity states with different electronic configurations, where the atoms are detected by photoionization process using an ultraviolet laser with a wavelength of 355 nm. Precise measurements on the energy level and intensity for many Sm 4f^6 6s6p and 4f^5 5d6s^2 states have been carried out. In a theoretical analysis on the spectral data, such as peak position, relative intensity, many transitions can be identified as the resonances from the Sm 4f^6 6s^2 7FJ （J=0-6） states to the atomic states with 4f^6 6s6p and 4f^5 5d6s^2 electronic configurations. This work also reports many spectral data on the odd-parity states that cannot be found in the literature.     

钐原子的两步激发共振光电离光谱

采用两步激发共振光电离技术研究了Sm原子的偶宇称高激发态光谱.实验采用了两条激发路线：1)第一束激光的波长固定在478.44nm以便将Sm原子从4f⁶6s²［⁷F₁］态激发至4f⁶6s6p［⁷D₁］态,再用第二束激光使其波长从480nm扫描至530nm,将Sm原子进一步激发至待测的高激发态;2)第一束激光的波长固定在574.8 关键词： Sm原子 光谱 分步激发 共振电离     

Application of electric field ionization method to detect the high-lying Rydberg states of Eu I

The 4f~76s(~9S)np 8 P J (J = 5/2, 7/2, 9/2) Rydberg series converging to the first ionization limit 4f 7 6s 9 S 4 of the Eu atom using the three-step laser excitation and electric-field-ionization (EFI) method are studied. First, the Eu atom is excited from the 4f 7 6s 2 8 S o 7/2 ground state to the 4f 7 6s7s 8 S o 7/2 state through the 4f 7 6s6p 10 P 9/2 state by the first two dye lasers. Next, it is populated to many higher-n members of the 4f 7 6s( 9 S)np 8 P J Rydberg series by the third dye laser whose wavelength is scanned within a certain range. Finally, the atom in these higher-n states is ionized by the external pulsed electric field. With the field strength up to 2 kV/cm, we can detect the atom in 4f 7 6s(9 S)np 8 P J states with n 40. With the given laser line width, the level energies of Rydberg states with n as high as 72 can be determined. We not only confirm the previous data on the 4f 7 6s(9 S) np 8 P J Rydberg series, but also extend the n-value assignment significantly by detecting more states.     

Investigation of autoionization spectra of Sm atom usingisolated-core excitation method

<正>Using the isolated-core-excitation scheme and three-step laser resonance ionization spectroscopy approach,this paper,for the first time,has systematically investigated the autoionization spectra of atomic Sm,belonging to the 4f~66pnl and 4f~55d6snl(l=0,2) configurations.In the experiment,the first two tunable dye lasers are employed to excite the Sm atom from its initial state to the different 4f~66snl bound Rydberg states,then the third dye laser is scanned to drive the atom to the doubly-excited autoionizing states.With the above excitation scheme,the measured transition profiles of the autoionizing states are nearly symmetric,from which the level energies and widths can be easily obtained.     

A study on odd-parity high-lying states of the Sm atom with three-color resonant excitation

The odd-parity high-lying states of the Sm atom are investigated systematically by a three-color resonant excitation scheme with two different excitation paths.The two intermediate states,4f 6 6s7s 7 F 0 and 4f 6 6s7s 7 F 1 are employed for paths I and II,respectively.Fifty-seven bound states are detected with paths I and II in the energy range between 44188 and 45515 cm 1,while 64 autoionizing states are found in the energy range from 45528 to 45761 cm 1.Not only the level energies of all observed states,b...     

Eu原子4f~76p_(3/2)6d自电离过程的动力学特性

采用孤立实激发技术(isolated-core excitation, ICE)及速度影像技术(velocity-map imaging,VMI),研究了Eu原子4f~76p_(3/2)6d自电离过程的动力学特性.孤立实激发技术用于将Eu原子从基态4f~76s~(2 8)S_(7/2)经中间态4f~76s6p激发到4f~76s6d里德堡态,然后将其进一步激发至4f~76p_(3/2)6d自电离态;速度影像技术用于探测其自电离过程的动力学特性,从而获得自电离衰变的分支比(branch ratio, BR)和弹射电子的角分布(angular distribution, AD).自电离衰变的分支比代表离子的能量分布,从中获得VMI影像的径向信息;而通过各向异性参数描述的弹射电子的角分布揭示了VMI影像的角向信息.此外,讨论了自电离衰变分支比和弹射电子角分布在整个自电离共振能域内的变化情况.基于4f~76s~+和4f~75d~+两个离子态的分支比,讨论了实现Eu离子粒子数反转的可能性.     

Experimental study of highly excited even-parity bound states of the Sm atom

In this work, a three-step autoionization detection method and direct photoionization detection method are employed to measure the highly excited even-parity states of the Sm atom in the energy region between 36360~cm^-1 and 40800~cm^-1. Comparisons between the results from the two detection techniques enable us to discriminate the Rydberg states from the valence states in the same energy region with the information of level energies, possible J values and their relative intensities. Furthermore, in the experiment two different excitation schemes are designed to obtain the spectra of highly excited even-parity states of the Sm atom. With a detailed analysis of the experimental data, this work not only confirms the results about many spectral data from the literature with different excitation schemes, but also reports new spectral data on 29 Rydberg states and 23 valence states.