钠分子高位2~1Ⅱ_g与C~1Ⅱ_u态之间的碰撞能量转移

通过双光子激发和探测后向受激辐射光谱的方法观察了钠分子高位单态2~1Π_g与C~1Π-x间的碰撞能量转移过程。理论上计算的C~1Π_x态的布居分布和由C~1Π_x→X~1∑_g~+跃迁产生的紫外受激辐射光谱,均与实验结果相符。还同时采用二台不同波长的染料激光器分别激发钠分子和钠原子,研究了不同激发态钠原子对钠分子高位激发态能量转移过程的影响。     

钠分子1Πg里德堡态光谱研究

通过光学-光学双共振(OODR)光谱方法,研究了钠分子六个高激发1Πg态,对它们进行了振动和转动归属,获得了分子常数和势能曲线.根据里德堡轨道的nlλ特性,将1～101Πg态划分为实贯穿里德堡态和实非贯穿里z德堡态.     

钠分子^1Пg里德堡态光谱研究

通过光学－光学以共振（ＯＯＤＲ）光谱方法,研究了钠分子六个高激发＾１Пｇ态,对它们进行了振动和转动归属,获得了分子常数和势能曲线。根据里德堡轨道的ｎｌλ特性,将１－１０＾１Пｇ态划分为实贯穿里德堡态和实非贯穿里堡态。     

钠原子连接的C_(60)富勒烯二聚物的等离激元激发

基于含时密度泛函理论,研究了钠原子连接的C60富勒烯二聚物的等离激元激发。由于碱金属钠原子和C60分子之间的耦合,在红外光谱区,钠原子连接的C60富勒烯二聚物出现了等离激元共振激发。随着C60分子之间间隙的逐渐减小,红外光谱区的等离激元先发生红移,之后发生了蓝移。在间隙较大,C60分子间电容性相互作用时,中红外光谱区的等离激元是一种多极共振模式。在间隙较小时,由于电子的隧穿,中红外光谱区的等离激元逐渐演化为近红外光谱区的另外一种等离激元共振模式,该等离激元共振模式是长程电荷转移激发模式和多极共振模式的耦合。     

拉曼光谱与拉曼效应的量子模型结构分析

散射光谱这种新谱线对应于散射分子中能级的跃迁,为研究分子结构提供了一种重要手段,引起学术界极大兴趣,拉曼也因此荣获1930年诺贝尔物理学奖。并称这种谱线为拉曼光谱。介绍了拉曼光谱的基本原理、拉曼光谱的应用以及其发展,由于拉曼光谱非常弱,实验要求比较高,最后介绍了实验仪器及利用拉曼光谱研究分子的结构。     

钠分子里德堡能级的无多普勒加宽光光三共振光谱以及能级宽度和谱…

首次报道了钠分子一系列里德堡能级的无多普勒加宽光光三共振激发荧光光谱，测量了其谱线宽度和其谱线位置随温度、外加气体压力的变化情况。结果表明，钠分子里德堡能级的自然宽度在６０－１３０ＭＨｚ之间，其大小主要与主量子数ｎ有关。     

基于振动光谱成像技术的聚合物共混体系研究进展

振动光谱可以提供分子的振动信息,对于聚合物分子链的构象和链间的相互作用非常敏感。分子振动光谱成像作为一种原位无损检测技术,广泛应用于聚合物共混体系结晶、相态分布、界面扩散等性质的研究。本文综述了拉曼(Raman)光谱和红外(IR)光谱成像技术以及其衍生的具有高空间分辨率的红外-原子力联用技术(IR-AFM)、拉曼-原子力联用技术(Raman-AFM)以及针尖增强拉曼光谱技术(TERS)在聚合物共混体系研究中的最新应用进展,以探索并扩展振动光谱成像技术在高分子领域中的应用。     

基于碰撞产生的频域和时域内的量子干涉效应研究

从理论和实验两方面对以往较少涉及的原子-分子混合体系中基于碰撞而产生间距较大多能级间的相干和两延时波包间的相干及量子干涉效应进行研究,揭示通过碰撞这种非相干过程可产生在频域内具有较大能级间距多能级间的相干和时域内两延时波包间的相干.运用半经典密度矩阵理论及缀释态理论对碰撞产生的多能级系统量子干涉效应进行计算和分析;同时实验上用ns脉冲染料激光器观察到钠原子-分子混合体系中基于等频双光子两步激发及钠原子-分子混合激发而产生的钠原子3S-3P(1/2,3/2)-5S(或4D)系统基于碰撞产生的频域和时域内的量子干涉效应.本工作为进一步运用非相干碰撞过程研究较大间距多能级间和两延时波包间的相干提供了一种新的有效的方法,可望在高灵敏高精度激光光谱、原子分子激发态结构信息及物理化学过程的控制等方面具有广泛的应用.     

最优化参数控制提高超冷铯分子振转光谱的信噪比

超冷原子光缔合光谱对于研究长程分子势能结构、分子常数和分子相关动力学过程具有重要意义.光缔合光谱的信噪比作为衡量探测技术的重要指标之一,直接影响光谱的分辨能力和探测灵敏度.利用调制荧光光谱技术获得了超冷长程铯分子超精细振转光谱.通过研究解调参数,即积分时间和灵敏度,发现解调参数对光谱信号的信噪比有重要影响,且依赖关系呈非线性.结合相关实验系统,实现了对光谱信噪比的最优化控制,为进一步研究超冷铯分子长程态振转能级结构奠定了重要的实验基础.     

钠分子B~1Π_u→X~1Σ_g~+LIF光谱及其强度研究

实验获得了Ar~+激光488nm线诱导Na_2分子产生B~1Π_u→X~1Σ~+_g跃迁荧光谱,其谱线的跃迁机制是分属于不同Q、P、R支系列的较高转动能级的B~1Π_u→X~1Σ~+_g电子态跃迁。研究了钠蒸气温度对Na_2分子激光诱导荧光光谱强度的变化关系,表明是由于荧光跃迁的上下能级不同弛豫过程的影响。分析了缓冲气体Ar对Na_a分子B~1Π_u态的碰撞猝灭作用,得出谱线强度与总气压的等轴双曲线关系,所得数据拟合曲线与实验很好地一致。     

NO2分子里德堡态的光学-光学双共振多光子离化谱

采用光学-光学双共振多光子离化（Optical-optical double-resonant multiphoton ionization，简称OODR-MPI）技术详细研究了NO2分子里德堡态的能级结构。结果显示，用不同强度的激光作抽运光，尽管NO2分子的OODR-MPI谱均由规则的光谱序列组成，但NO2分子的离化通道存在很大区别，当抽运光强度较高时，NO2分子通过(3+1+1)双共振多光子过程离化；而当抽运光强度较低时，NO2分子通过(1+2+1)双共振多光子过程离化，两种离化机制的最终共振能级属于不同的里德堡态。     

氩原子共振增强多光子电离谱--奇对称性里德堡态

利用脉冲放电产生氩原子亚稳态4s2[3/2]°2和4s′2[1/2]°0,在610～670nm波长范围内,利用共振增强多光子电离和飞行时间质谱技术得到氩原子(2+1)REMPI谱.光谱分析表明所有谱线来源于氩原子4s2[3/2]2和4s′2[1/2]°0两个亚稳态向16个奇对称性里德堡态双光子跃迁,并标识所有谱线.同时首次在实验上观察到一个长序列的3p54s′2[1/2]°0→3p5nd2[1/2]°1(n=8～31)双光子跃迁.在实验技术上,提供了一种研究惰性气体原予以及其它原子高里德堡态和自电离态的新方法.     

Rydberg spectroscopy in an optical lattice: blackbody thermometry for atomic clocks

We show that optical spectroscopy of Rydberg states can provide accurate in situ thermometry at room temperature. Transitions from a metastable state to Rydberg states with principal quantum numbers of 25-30 have 200 times larger fractional frequency sensitivities to blackbody radiation than the strontium clock transition. We demonstrate that magic-wavelength lattices exist for both strontium and ytterbium transitions between the metastable and Rydberg states. Frequency measurements of Rydberg transitions with 10(-16) accuracy provide 10 mK resolution and yield a blackbody uncertainty for the clock transition of 10(-18).     

双光子共振非简并四波混频测量Ba原子里德伯态的碰撞展宽和频移

采用双光子共振非简并四波混频测量了Ar缓冲气压引起的Ba原子里德伯6snd ¹D₂谱线系的碰撞展宽和频移, 计算了n=16---33的碰撞展宽截面和频移截面. 本方法是一种纯光学的测量技术, 当采用窄带激光器时可以获得里德伯态的消多普勒光谱. 与传统实验方法测量到的里德伯态纵向弛豫的碰撞展宽不同, 本方法可以研究碰撞引起的两能态间横向弛豫的展宽.     

The spectrum of SiO in the vacuum ultraviolet region

The absorption spectrum of SiO has been photographed at high resolution in the region 1200–1500 Å. Several new electronic states have been observed, valence states as well as Rydberg states. Tables of the molecular constants of all the known states of SiO are given. Due to interactions between the electronic states, the constants of all states analyzed vary irregularly. From the Rydberg series a value of the ionization potential has been derived. It agrees with the value earlier reported, 11.6 ± 0.2 eV.     

Rydberg states in the condensed phase studied by fluorescence depletion spectroscopy

Higher Rydberg states of NO trapped in rare gas matrices have been studied by inducing Rydberg-Rydberg transitions from the lowest Rydberg state and detecting its fluorescence depletion. This technique unravels Rydberg states, which cannot be accessed by ground state absorption. However, no clear cut Rydberg series show up. The data show a compression of the n-(n + 1) splittings between Rydberg states, as well as of the splittings. The results are rationalised in terms of the quantum defect model and the lack of extended Rydberg series is due to the compression of high-n Rydberg states in a tiny energy region below the ionisation potential. Finally, fluorescence depletion data of NO trapped in amorphous sites (the so-called red sites) of solid Ar can be interpreted in terms of the gas phase NO-Ar van der Waals data. A general discussion on the fate of Rydberg states in van der Waals complexes, in liquids, and in solids is presented in an attempt to relate the data in these different media. Received 28 July 1999 and Received in final form 8 November 1999     

Observation of inner electron ionization from radial rydberg wave packets in two-electron atoms

We have observed multiphoton ionization of the 5s core electron from a 5snd radial Rydberg wave packet of Sr atoms using a short optical pulse. When the outer nd electron is at its outer turning point the inner 5s electron is removed from the atom, and the outer electron is left in a Sr+ Rydberg state, but when the outer electron is at the inner turning point this does not occur. Analysis of the final Sr+ Rydberg states shows that the two electrons interact as the inner electron leaves, so that the outer electron is not simply projected onto the Sr+ Rydberg states.     

Observation of the Dipole Blockade Effect in Detecting Rydberg Atoms by the Selective Field Ionization Method

The dipole blockade effect at laser excitation of mesoscopic ensembles of Rydberg atoms lies in the fact that the excitation of one atom to a Rydberg state blocks the excitation of other atoms due to the shift in the collective energy levels of interacting Rydberg atoms. It is used to obtain the entangled qubit states based on single neutral atoms in optical traps. In this paper, we present our experimental results on the observation of the dipole blockade for mesoscopic ensembles of 1–5 atoms when they are detected by the selective field ionization method. We have investigated the spectra of the three-photon laser excitation 5S1/2 → 5P3/2 → 6S1/2 → nP3/2 of cold Rydberg Rb atoms in a magneto-optical trap. We have found that for mesoscopic ensembles this method allows only a partial dipole blockage to be observed. This is most likely related to the presence of parasitic electric fields reducing the interaction energy of Rydberg atoms, the decrease in the probability of detecting high states, and the strong angular dependence of the interaction energy of Rydberg atoms in a single interaction volume.     

用于真空紫外光吸收和光电离截面测量的多电极光电离室装置

详细介绍了所制的多电极真空紫外光电离室实验装置。它主要由光学聚焦系统、真空系统、多级光电离吸收室和数据采集系统四部分组成。其主要特点是使用圆筒形多级电极收集光电离产生的电子和离子，并能精确地测量分子的绝对光吸收、光电离和光离解截面，以及光电离量子产率和光学振子强度分布等。结合光电离质谱技术，可获得碎片离子的部分光电离截面。最后给出初步实验结果。     

Coherent optical detection of highly excited Rydberg states using electromagnetically induced transparency

We demonstrate coherent optical detection of highly excited Rydberg states (up to n=124) using electromagnetically induced transparency (EIT), providing a direct nondestructive probe of Rydberg energy levels. We show that the EIT spectra allow direct optical detection of electric field transients in the gas phase, and we extend measurements of the fine structure splitting of the nd series up to n=96. Coherent coupling of Rydberg states via EIT could also be used for cross-phase modulation and photon entanglement.