Autoionization spectra of Sm atom

Spectra of autoionizing states of the Sm atom in an energy region between 45948.9 cm-1 and 46943.6 cm-1 are systematically investigated by a three-color multi-step resonant excitation scheme with three different excitation paths.The three intermediate states,4f 66s7s 7F3,4f 66s7s 7F4,and 4f 66s7s 9F5 are employed for the three paths,respectively.Based on precise calibration of wavelength,the level energies of 112 autoionizing states are determined with the line widths and the relative line intensities of the related transitions.The possible influence of configuration interaction on the line shape of autoionizing state is also discussed.In addition,a unique value of J,the total angular momentum,is assigned to all detected states by comparing the three spectra obtained with the different excitation paths.     

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.     

Branching ratios of autoionization from Eu 4f~76p_(1/2)6d [J] autoionizing states

The autoionization branching ratios from Eu 4f76p1/26 d [J] autoionizing states to its 4f76s+(9So), 4f76s+(7So), and4f75d+(9Do) final ionic states are investigated with the combination of the three-step laser excitation and the velocity-map imaging technique. These different autoionizing states are excited via 4f76s6d8 DJ [J = 5/2, 7/2, and 9/2] intermediate states, respectively. The experimental photoelectron images are obtained, from which energy distributions of ejected electrons are achieved with the mathematical transformation. Furthermore, the energy dependence of the branching ratio is investigated within the autoionization resonance, by which population inversion is observed as an important characteristic.The J-dependence is also studied systematically. The validity of the well-known isolated core excitation technique used for obtaining the autoionization spectrum is also studied.     

Even-parity states of the Sm atom with stepwise excitation

Two-colour stepwise excitation and photoionization schemes are adopted to study the spectra of high-lying states of the Sm atom. These bound even-parity states are excited with three different excitation paths from the 4f66s6p7DJ (J = 1, 2, 3) intermediate states, respectively. They are probed by photoionization process with an extra photon driving them to the continuum states. In this experiment, 270 states are detected in an energy range from 36160 cm-1 to 42250 cm-1, 109 of which are newly discovered, while the rest of them are confirmed to be the energy levels reported previously. Furthermore, based on the J-momentum selection rules of three excitation paths, a unique assignment of J-momentum for all observed states is determined, eliminating all remaining ambiguities in the literature. Finally, 53 single-colour transitions originating from the scanning laser are also identified. For all the relevant transitions, the information about their relative intensities is also given in the paper.     

掺杂三价铽离子的碱土金属钨酸盐的光谱特性研究

本文合成了一系列掺杂三价铽离子的碱土金属钨酸盐,测定了晶体的X射线粉末衍射数据及发射光谱和激发光谱.所合成的化合物均属四方晶系,I41/a空间群,晶胞多数随金属离子半径的增大而增大.研究了在这些晶体中三价铽离子5D3→7Fi和5D4→7Fi跃迁发射的激发态及其能量传递机理和浓度猝灭机制.讨论了发射光谱和激发光谱与铽离子浓度、金属离子半径及铽离子在晶体中的溶解度的关系.     

Photoionization spectra of even-parity states of Sm atom with multistep excitation

Two-color stepwise excitation and photoionization schemes are adopted to study the spectra of bound even-parity high-lying states of the Sm atom with three different excitation paths via the 4f⁶6s6p ⁷D_J (J=1, 2 and 3) intermediate states. In order to obtain the information of these high-lying states, the Sm atom in these high-lying states is photoionized with an extra photon. Among 231 states detected in the energy region between 35,545 and 44,225 cm⁻¹, 108 states are newly discovered, while the rest can be identified as the same with the literature. In most cases, comparisons of the spectra corresponding to the three different excitation paths may partially determine the total angular momentum of the observed peaks with the selection rules. In addition, the relative intensities of all related transition lines are given.     

铕原子4f76p3/2nd自电离态的光谱

利用三步三色孤立实激发技术(ICE),系统地研究了铕原子4f76p3/2 nd自电离态的光谱,同时首次研究了激光偏振对复杂原子的光谱的影响.为了研究铕原子4f76p3/2 nd自电离态的光谱,首先设计并采用了不同的激发路径,分别将原子布居到同一高激发能域并探测它们在该能域的自电离光谱.通过比较这些光谱的异同并结合上述激发路径所对应的跃迁选择定则,便可唯一地确定这些高激发态的总角动量.为了研究激光偏振对铕原子的影响,设计并使用了两种偏振组合:三步激光都是垂直(πππ),三步激光都是平行(σσσ)(激光偏振方向相对于探测器垂直或平行).为了得到有偏振影响的光谱,分别使3部激光器处于同一偏振,依次对铕原子进行激发,激发路径与终态同上.通过对同一路径不同偏振下的光谱的比较,发现仅能确定极少数的高激发态的总角动量,同时在光谱中一些峰独立于另一偏振光谱存在.     

Cs(8S)态的碰撞转移和高位原子态的激发

在Cs蒸气中,二步激发Cs原子至8S态,研究了其碰撞转移和高位原子态的产生过程.在1016～1017 cm-3密度范围内,测量了碰撞激发转移8S 6S→6D 6S的速率系数.由测得的荧光强度随密度的变化关系,得到k6D=(2.4±0.5)×10-10 cm3·s-1.同时研究了碰撞能量合并过程5D 5D→nL 6S(nL=9D,11S,7F),5D态是由8S→7P→5D的辐射跃迁产生的.由以前测量过的6P 5D 6S 7D的转移速率系数以及6P态的原子密度,结合荧光强度比得到碰撞能量合并过程的速率系数,对于9D,11S和7F各态,其平均值分别为(6.4±3.2)×10-10,(1.0±0.5)×10-10和(8.4±4.2)×10-10 cm3·s-1.     

Investigation of odd-parity Rydberg states of Eu I with autoionization detection

Isolated-core-excitation (ICE) scheme and autoionization detection are employed to study the bound Rydberg states of europium atom. The high-lying states with odd parity have been measured using the autoionization detection method with three different excitation paths via 4f⁷6s6p[ ⁸P_5/2], 4f⁷6s6p[ ⁸P_7/2] and 4f⁷6s6p[ ⁸P_9/2] intermediate states, respectively. In this paper the spectra of bound Rydberg states of Eu atom are reported, which cover the energy regions from 36000~cm^-1 to 38250~cm^-1 and from 38900~cm^-1 to 39500 cm^-1. The study provides the information about level energy, the possible J values and relative line intensity as well as the effective principal quantum number n^* for these states. This work not only confirms the previous results of many states, but also discovers 11 new Rydberg states of Eu atom.     

Optical spectroscopy of Ce 3+ ions in BaY 2 F 8 single crystals

In the present work we report on the spectroscopic properties of the Ce 3+ ion in BaY 2 F 8 single crystals. The absorption and excitation spectra of the emission centered at 340 v nm have been measured in the temperature range 15-300 v K. The 340 v nm emission consists of two broad partially overlapping bands, peaking at 324 and 347 v nm (at 15 v K), respectively. The full width at half maximum is about 0.5 v eV at room temperature. The absorption spectrum of the lowest in energy component of the f M d transition of Ce 3+ reveals at low temperature a marked vibronic structure. High resolution (0.02 v cm m 1 ) Fourier transform infrared spectroscopy in the wave number range 500-5000 v cm m 1 and in the temperature range 9-300 v K has been exploited to monitor the f level splitting. The absorption transitions from the three Stark components of the 2 F 5/2 manifold to the four of the 2 F 7/2 one, have been monitored in the wave number range 2000-3400 v cm m 1 . The wave number separation at 9 v K between the lowest level of the ground 2 F 5/2 manifold and lowest one of the 2 F 7/2 manifold is found to be 2197.47 v cm m 1 in good agreement with the splitting detected between the two components of the d M f emission.     

Tb3+掺杂Y2O3纳米晶体中Tb3+离子4f5d跃迁及能量传递的研究

采用燃烧法制备了不同Tb3 掺杂浓度和不同粒径的Y2O3:Tb纳米晶体粉末样品,并通过高温退火获得了相应Tb3 掺杂浓度的体材料样品。测量了纳米和体材料样品的发射光谱、激发光谱、X射线衍射谱和荧光衰减曲线,并拍摄了不同粒径样品的透射电子显微镜(TEM)照片。研究纳米Y2O3∶Tb晶体粉末中Tb3 离子的4f5d跃迁发现,由于在近表面的低结晶度环境和颗粒内部的高结晶度环境中Tb3 离子4f5d跃迁对应的激发峰位置不同,不同粒径样品中处于这两种环境的Tb3 离子比例也不同,激发谱的谱线形状存在较大差别,还对Tb3 离子的能量传递进行了研究,发现Y2O3∶Tb晶体粉末中Tb3 的(5D3,7F6)→(5D4,7F0)能量传递类型为受纳米限域效应影响很大的电偶极电偶极相互作用;引起5D4→7F5(543nm)发光浓度猝灭的是不同Tb3 离子5D4能级之间交换相互类型的能量传递,此类型的能量传递受纳米限域效应影响较小。     

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.     

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。     

Cs_2NaYF_6:Ho~(3+)的电子光谱与能级结构分析

综合运用稀土光谱理论、量子力学、晶体场理论对高对称稀土离子Cs2NaYF6:Ho3+的电子光谱与能级结构展开了深入的研究。4600～24000cm-1范围内不同温度下的电子吸收光谱清楚的记录了从基态到不同激发态5FJ(J=7,6,5,4),5FS(S=5,4,3),5GP(P=6,5)及3K8的跃迁。这些跃迁表现为零声子线(ZPL)及丰富的振动结构。由光谱解析结果得到50个Ho3+的能级数据,还运用标准f-shell程序进行能级拟合及晶场分析,得到Cs2NaYF6:Ho3+能级的计算值及相应的哈密顿量参数。同时,对同类冰晶石晶格中不同配体(Cs2NaYF6:Ho3+,Cs2NaYCl6:Ho3+)的能级及拟合参数进行了对比。     

Eu原子4f~76snlRydberg态的研究

利用三步双色共振激发技术和三步三色孤立实激发技术,系统地研究了铕原子在42250—44510 cm~(-1)能域内的光谱特性,提供了该能域内56个束缚高激发态的光谱信息.为了能确定这些态的光谱归属,进行了两方面的探索:第一,观察能否利用孤立实激发技术,把处于这些态上的铕原子进一步共振激发到自电离态,从而推断这些态属于单电子激发的束缚Rydberg态还是属于双电子激发的价态,并对Rydberg态的电子组态进行了光谱确认;第二,通过计算这些态相对于各个电离阈的量子亏损并观察它们分别收敛于哪个电离阈,以便获取其主量子数的信息.最后,设计并采用了三种不同的激发路径,分别将原子布居到同一高激发能域并探测它们在该能域的光电离光谱.通过比较这些光谱的异同并结合上述激发路径所对应的跃迁选择定则,便可惟一地确定这些高激发态的总角动量.研究发现:所探测到的高激发束缚态只有三个属于单电子激发的束缚Rydberg态,其余都是价态.本文确定了这三个Rydberg态的电子组态和原子状态.     

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 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.     

利用光电离技术研究奇宇称的Sm原子光谱

采用一台频率可扫描的染料激光器将Sm原子从4f66s2 7FJ(J=1,2)态分别激发到具有不同电子组态的若干原子态上,然后利用光电离技术对处于上述状态的Sm原子进行高灵敏探测.通过波长固定在355nm的紫外激光器,我们对一系列具有4f66s6p或者4f55d6s2电子组态的原子状态进行了精密的光谱测量.本实验研究不但确定了这些态的能级位置,还给出了它们的相对光谱强度.通过理论方法对光谱数据详细的分析,我们不但确认了文献中Sm原子的部分奇字称能级的位置和光谱标识,还同时给出了许多新的跃迁及其光谱特性.     

Inter- and intraconfigurational luminescence of Er 3+ ions in BaY 2 F 8 under VUV excitation

Using energy- and time-resolved spectroscopy the luminescence properties of Er 3+ doped BaY 2 F 8 crystals were investigated at 10 v K under VUV synchrotron radiation excitation. Radiative intraconfigurational f - f and interconfigurational d - f transitions in Er 3+ ions were observed under f - d excitation. Whereas the onset of 4 S 3/2 population via f - d excitation starts at 59 900 v cm m 1 , efficient excitation of emissions arising from the 2 P 3/2 state begins only above 67 000 v cm m 1 in VUV region. Such behaviour can be explained by a cross-relaxation process of the type ( 2 F(2) 5/2 , 4 I 15/2 ) M ( 2 P 3/2 , 2 P 3/2 ) taking place within f -states of Er 3+ ions finally populating the emitting 2 P 3/2 state.     

锂分子3^1Ⅱg里德堡态的光谱研究

我们用脉冲光学-光学双共振荧光激发谱（OODR），测量了在35500-38000cm^-1能量范围内的里德堡态，观察到^7Li23^1Ⅱg态的10个振动能，本文观测的3^1Ⅱg态的146条激发谱线进行了归属，得到了新的Dunhm常数，RKR势能曲线以及A^1∑u^ 到3^1Ⅱg态跃迁的夫兰克-康登因子，并且讨论了3^1Ⅱg态的双重分裂以及与附近里德堡态F（4）^1∑g^ ,5^1∑g^ ,6^1∑g^ 和G（2）^1Ⅱg的微扰，发现在我们的实验精度下（0.2cm^-1)3^1Ⅱg态掇重分裂可以忽略。