双奇核188Tl高自旋态能级结构研究

本论文首先介绍了在束谱学实验技术研究原子核高自旋态的基础理论知识，然后描述了实验数据的处理方法。在此基础上，详细分析并讨论了188Tl核高自旋态能级结构的性质。利用能量为170 MeV 的35Cl束流,通过157Gd(35Cl,4n)熔合蒸发反应研了188Tl的高自旋态能级结构。基于实验结果，建立了188Tl基于质子h9/2

187Pt的高自旋态能级结构研究

利用在束γ谱学技术和 173Yb(18O, 4n) 熔合蒸发反应研究了 187Pt 的高自旋态能级结构。在 78 和 85 MeV 束流能量下进行了X-γ-t和γ-γ-t符合测量。实验观测到基于νi13/2，ν7/2−[503]，νi213/2νj, ν3/2−[512] 和ν1/2−[521] 组态的转动带，并且利用推转壳模型(CSM) 和总Routhian面(TRS) 模型对这些转动带的带交叉，形状共存等性质进行了解释。总Routhian面(TRS)计算表明νi13/2转动带具有显著的负γ形变；负宇称带具有近似长椭球的形变。通过比较带内B(M1)/B(E2)比率的实验值和由 Dönau 和 Frauendorf 的半经典公式得到的理论值，发现ν7/2−[503] 转动带在低转动频率下的带交叉是由一对 h9/2 质子顺排引起的

原子核145Tb和157Yb的高自旋态能级结构研究

本论文分为两部分：1）利用能量为165 Mev的飞束流，通过熔合蒸发反应118Sn（32S，1p4n），用12套BGO（AC）HPGe探测器进行了γ射线的激发函数、X-γ-t和γ-γ-t符合测量。首次建立了由50个能级、81条γ跃迁组成的145Tb的高自旋态能级纲图。基于邻近N＝80同中子素能级结构的系统性，用弱祸合模型对145Tb的低位能级结构进行了解释。145Tb的低位能级可以看成是由一个hll尼价质子与偶偶核芯144Gd的2＋，4＋和3-激发态祸合而成。通过粒子一核芯相互作用计算很好地再现了145Tb的低位激发态。通过比较可知，（πh11/2⑧v-22+，4+）和（πh11/2×3-）多重态的激发能与相应核芯的激发态能量相差不大，这说明价质子与核芯的相互作用比较弱。本工作在多粒子壳模型组态基础上对145Th的更高激发态进行了深入讨论。为了使实验能级的组态指定更为直接方便，采用了参数无关的半经验壳模型计算。其结果清楚地揭示了球形核多准粒子的激发特性。通过与计算结果比较，明确地指定了晕态能级和部分非晕态能级的组态。 2）利用能量为90MeV的16O束流，通过144Sm（16O，3n）反应，用11套BGO（AC）HPGe探测器进行了长时间的γ-γ-t符合测量。基于γ-γ符合关系、γ射线的各向异性度和DCO系数的测量结果，首次建立了157Yb的高自旋能级纲图。确定了157Yb的13／2+同质异能态的激发能为530 keV。此同质异能态已经被前人指定，其激发能却一直未知。观测到了157Yb的vi13/2龙转动带。157Yb能级纲图中的角动量较低部分显示了轻微扁椭与长椭形变之间的共存。随着角动量增加，157Yb的vi13/2带逐渐损失其集体性，其能级结构演变为具有准振动的激发样式，最后被单粒子激发所取代。用TRs模型计算了157Yb的vi13/2转动带随着角动量增加的形状演变。计算结果很好地再现了实验观测。本工作表明，157Yb不但在核素图上连接了基态为球形（N＜87）和有明显长椭球形变（N＞87）的2组同位素，而且同时具有这2组同位素的结构性质。

双奇核190Tl和146Tb高自旋态能级结构研究

本论文介绍了原子核高自旋态研究的一般概况及有关核模型，描述了在束γ谱实验的原理与技术、数据分析与处理方法，然后着重分析和讨论了双奇核190Tl和146Tb高自旋能级结构的特性。 利用能量为175和167MeV的35Cl束流，通过反应160Gd(35Cl,5n)研究了双奇形变核190Tl的高自旋能级结构。实验进行了γ射线的激发函数和各向异度、X-γ和γ-γ-t符合测量，建立了由πh9/2νi13/2扁椭球转动带和一个具有单粒子激发特征的级联组成的190Tl能级纲图。确定地指定了190Tl的转动带自旋值，首次发现了190Tl πh9/2νi13/2扁椭球转动带的低自旋旋称反转。基于双奇核Tl能级结构的相似性，重新指定了双奇核192-200Tl πh9/2νi13/2扁椭球转动带能级自旋值，澄清了二十多年来国际上一直没有解决的自旋值指定问题且在这些扁椭形变核中均出现了低自旋旋称反转。考虑了p-n剩余相互作用的2-准粒子—转子模型定性地解释πh9/2νi13/2扁椭球转动带出现的低自旋旋称反转现象。 利用118Sn(32S ,1p3n)反应研究了双奇球形核146Tb的高自旋态，建立了激发能达8.39 MeV的能级纲图，其中包括新发现的41条γ射线和新建立的27个能级，并指定了新发现能级的自旋值和部分能级的组态。146Tb81的低位激发态是二准粒子态，高位的激发态是四准粒子态，或二准粒子与偶偶核芯低位激发态的耦合，更高位的能级则是六准粒子态，甚至八准粒子态。利用经验壳模型对部分全顺排组态的激发能进行了理论计算

双奇核188Tl高自旋态能级结构研究

本论文首先介绍了在束谱学实验技术研究原子核高自旋态的基础理论知识，然后描述了实验数据的处理方法。在此基础上，详细分析并讨论了188Tl核高自旋态能级结构的性质。利用能量为170 MeV 的35Cl束流,通过157Gd(35Cl,4n)熔合蒸发反应研了188Tl的高自旋态能级结构。基于实验结果，建立了188Tl基于质子h9/2

187Pt的高自旋态能级结构研究

利用在束γ谱学技术和 173Yb(18O, 4n) 熔合蒸发反应研究了 187Pt 的高自旋态能级结构。在 78 和 85 MeV 束流能量下进行了X-γ-t和γ-γ-t符合测量。实验观测到基于νi13/2，ν7/2−[503]，νi213/2νj, ν3/2−[512] 和ν1/2−[521] 组态的转动带，并且利用推转壳模型(CSM) 和总Routhian面(TRS) 模型对这些转动带的带交叉，形状共存等性质进行了解释。总Routhian面(TRS)计算表明νi13/2转动带具有显著的负γ形变；负宇称带具有近似长椭球的形变。通过比较带内B(M1)/B(E2)比率的实验值和由 Dönau 和 Frauendorf 的半经典公式得到的理论值，发现ν7/2−[503] 转动带在低转动频率下的带交叉是由一对 h9/2 质子顺排引起的

140Pr核高自旋态能级结构研究

本论文从内容上可以分为两大部分：第一部分：主要介绍原子核高自旋态研究的一般概况以及其物理解释的基本理论，然后介绍在束γ谱学及其实验技术，最后是介绍分析和处理实验数据的方法。第二部分：对近球形核l40Pr高自旋态进行的在束γ研究。这一部分是本文的重点。在对N＝82闭壳附近的奇A核和奇奇核如：141Nd、142Pm、l43Nd等研究中发现，它们的激发态具有典型的单粒子运动特征，并利用壳模型理论对它们的能级进行了很好的解释，对这一区域的典型的单粒子运动特征有必要进行深入地研究。由此，本论文利用在束γ谱学方法，通过130Te（14M，4n）熔合蒸发反应在束流能量55-65MeV范围内研究了双奇核140Pr的高自旋态能级结构。实验用十二台息G0（AC）HPGe探测器进行了γ射线的激发函数、γ射线单谱和γ-γ-t符合测量。基于上述实验测量，本工作首次建立了包括27个新能级和42条新y跃迁的刚Pr高自旋能级纲图，并且根据测量的ADO系数建议了140Pr部分能级的自旋值。根据140Pr周围双奇核结构的系统性，对它的部分高自旋能级的组态进行了讨论。在本工作之前，S.G.Hussein等人用140Pr（d,t）和140ce（p，nγ）反应研究了140Pr的低位能级结构；K.H.Schedl等人测量了140Pr两个同质异能态的寿命，而在同质异能态以上140Pr的在束丫谱学信息还是空白。

Electronic spectroscopy of thiones

The phosphorescence excitation spectra of two thiones, 4-H-1-xanthione (XT) and 4-H-1-pyrane-4-thione (PT), cooled in a supersonic jet were investigated. The vibronic lineshape of the T1z origin of PT measured by cavity ring-down spectroscopy is considered and the excited state rotational constants are calculated. For XT the 3A2(nπ* ) → X1A1 phosphorescence excitation spectrum was investigated in the region 14900-17600 cm-1. The structure observed is shown to be due to the T1← S0 absorption and an assignment in terms of the vibronic structure of the band is proposed. A previous assignment of the S1 ← S0 origin is considered and the transition involved is shown to be most probably due to the absorption of a vibronic tiplet state T1z,v7. An alternative but tentative assignment of the S1,0 ←S0,0 transition is suggested. In the case of PT the phosphorescence excitation spectrum was investigated in the region of the 1A2(ππ*) ← X1A1 absorption band between 27300 and 28800 cm-1. The spectrum exhibits complex features which are typical for the strong vibronic coupling case of two adjacent electronic states. The observed intermediate level structure was attributed to the coupling with a lower lying dark electronic state 1B1(nπ*2), whose origin was estimated to be ~ 825 - 1025 cm-1 below the origin of 1A2(ππ*)0. Consequences of the vibronic coupling on the decay dynamics of 1A2(ππ*) as well as tentative assignments of vibronic transitions 1A2(ππ*)v ← X1A1 are also discussed. In the T1z ← S0 cavity ring-down absorption spectrum of PT, the vibronic lineshape of the T1z origin is analysed. As the T1z line is separated from the T1x,1y lines by a large zero-field splitting it is possible to use an Asyrot-like program to calculate the vibrational-rotational parameters determining the lineshape. It is shown that PT is non-planar in the first excited triplet state and the lineshape is composed of a mixture of A-type and C-type bandshapes. The non-planarity of PT is discussed.

Optical Cooling Using the Dipole Force

The term `laser cooling' is applied to the use of optical means to cool the motional energies of either atoms and molecules, or micromirrors. In the literature, these two strands are kept largely separate; both, however suffer from severe limitations. Laser cooling of atoms and molecules largely relies on the internal level structure of the species being cooled. As a result, only a small number of elements and a tiny number of molecules can be cooled this way. In the case of micromirrors, the problem lies in the engineering of micromirrors that need to satisfy a large number of constraints---these include a high mechanical Q-factor, high reflectivity and very good optical quality, weak coupling to the substrate, etc.---in order to enable efficient cooling. During the course of this thesis, I will draw these two sides of laser cooling closer together by means of a single, generically applicable scattering theory that can be used to explain the interaction between light and matter at a very general level. I use this `transfer matrix' formalism to explore the use of the retarded dipole--dipole interaction as a means of both enhancing the efficiency of micromirror cooling systems and rendering the laser cooling of atoms and molecules less species selective. In particular, I identify the `external cavity cooling' mechanism, whereby the use of an optical memory in the form of a resonant element (such as a cavity), outside which the object to be cooled sits, can potentially lead to the construction of fully integrated optomechanical systems and even two-dimensional arrays of translationally cold atoms, molecules or even micromirrors.

Liouville-space R-matrix-Floquet description of atomic radiative processes involving autoionizing states in the presence of intense electromagnetic fields

A reduced-density-operator description is developed for coherent optical phenomena in many-electron atomic systems, utilizing a Liouville-space, multiple-mode Floquet–Fourier representation. The Liouville-space formulation provides a natural generalization of the ordinary Hilbert-space (Hamiltonian) R-matrix-Floquet method, which has been developed for multi-photon transitions and laser-assisted electron–atom collision processes. In these applications, the R-matrix-Floquet method has been demonstrated to be capable of providing an accurate representation of the complex, multi-level structure of many-electron atomic systems in bound, continuum, and autoionizing states. The ordinary Hilbert-space (Hamiltonian) formulation of the R-matrix-Floquet method has been implemented in highly developed computer programs, which can provide a non-perturbative treatment of the interaction of a classical, multiple-mode electromagnetic field with a quantum system. This quantum system may correspond to a many-electron, bound atomic system and a single continuum electron. However, including pseudo-states in the expansion of the many-electron atomic wave function can provide a representation of multiple continuum electrons. The 'dressed' many-electron atomic states thereby obtained can be used in a realistic non-perturbative evaluation of the transition probabilities for an extensive class of atomic collision and radiation processes in the presence of intense electromagnetic fields. In order to incorporate environmental relaxation and decoherence phenomena, we propose to utilize the ordinary Hilbert-space (Hamiltonian) R-matrix-Floquet method as a starting-point for a Liouville-space (reduced-density-operator) formulation. To illustrate how the Liouville-space R-matrix-Floquet formulation can be implemented for coherent atomic radiative processes, we discuss applications to electromagnetically induced transparency, as well as to related pump–probe optical phenomena, and also to the unified description of radiative and dielectronic recombination in electron–ion beam interactions and high-temperature plasmas.

Argon predissociation spectroscopy of the OH-center dot H2O and Cl-center dot H2O complexes in the 1000-1900 cm(-1) region: Intramolecular bending transitions and the search for the shared-proton fundamental in the hydroxide monohydrate

We present argon predissociation vibrational spectra of the OH-.H2O and Cl-.H2O complexes in the 1000-1900 cm(-1) energy range, far below the OH stretching region reported in previous studies. This extension allows us to explore the fundamental transitions of the intramolecular bending vibrations associated with the water molecule, as well as that of the shared proton inferred from previous assignments of overtones in the higher energy region. Although the water bending fundamental in the Cl-.H2O spectrum is in very good agreement with expectations, the OH-.H2O spectrum is quite different than anticipated, being dominated by a strong feature at 1090 cm(-1). New full-diniensionality calculations of the OH-.H2O vibrational level structure using diffusion Monte Carlo and the VSCF/CI methods indicate this band arises from excitation of the shared proton.

Gamma transition intensity determination using multidetector coincidence data

This work describes two similar methods for calculating gamma transition intensities from multidetector coincidence measurements. In the first one, applicable to experiments where the angular correlation function is explicitly fitted, the normalization parameter from this fit is used to determine the gamma transition intensities. In the second, that can be used both in angular correlation or DCO measurements, the spectra obtained for all the detector pairs are summed up, in order to get the best detection statistics possible, and the analysis of the resulting bidimensional spectrum is used to calculate the transition intensities; in this method, the summation of data corresponding to different angles minimizes the influence of the angular correlation coefficient. Both methods are then tested in the calculation of intensities for well-known transitions from a (152)Eu standard source, as well as in the calculation of intensities obtained in beta-decay experiments with (193)Os and (155)Sm sources, yielding excellent results in all these cases. (C) 2009 Elsevier B.V. All rights reserved.

Optical energy storage properties of Sr(2)MgSi(2)O(7):Eu(2+),R(3+) persistent luminescence materials

The details of the mechanism of persistent luminescence were probed by investigating the trap level structure of Sr(2)MgSi(2)O(7):Eu(2+),R(3+) materials (R: Y, La-Lu, excluding Pm and Eu) with thermoluminescence (TL) measurements and Density Functional Theory (DFT) calculations. The TL results indicated that the shallowest traps for each Sr(2)MgSi(2)O(7):Eu(2+),R(3+) material above room temperature were always ca. 0.7 eV corresponding to a strong TL maximum at ca. 90 A degrees C. This main trap energy was only slightly modified by the different co-dopants, which, in contrast, had a significant effect on the depths of the deeper traps. The combined results of the trap level energies obtained from the experimental data and DFT calculations suggest that the main trap responsible for the persistent luminescence of the Sr(2)MgSi(2)O(7):Eu(2+),R(3+) materials is created by charge compensation lattice defects, identified tentatively as oxygen vacancies, induced by the R(3+) co-dopants.

Theoretical analysis of the energy levels induced by oxygen vacancies and the doping process (Co, Cu and Zn) on SnO2 (110) surface models

Density functional calculation at B3LYP level was employed to study the surface oxygen vacancies and the doping process of Co, Cu and Zn on SnO2 (110) surface models. Large clusters, based on (SnO2)(15) models, were selected to simulate the oxidized (Sn15O30), half-reduced (Sn15O29) and the reduced (Sn15O28) surfaces. The doping process was considered on the reduced surfaces: Sn13Co2O28, Sn13Cu2O28 and Sn13Zn2O28. The results are analyzed and discussed based on a calculation of the energy levels along the bulk band gap region, determined by a projection of the monoelectron level structure on to the atomic basis set and by the density of states. This procedure enables one to distinguish the states coming from the bulk, the oxygen vacancies and the doping process, on passing from an oxidized to a reduced surface, missing bridge oxygen atoms generate electronic levels along the band gap region, associated with 5s/5p of four-/five-fold Sn and 2p of in-plane O centers located on the exposed surface, which is in agreement with previous theoretical and experimental investigations. The formation energy of one and two oxygen vacancies is 3.0 and 3.9 eV, respectively. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Nanostructure and luminescent properties of sol-gel derived europium-doped amine functionalised hybrids

The effect of doping by europium triflate on the nanoscopic structure of organic-inorganic hybrid formed by a siliceous network containing pendant amine-terminated propyl chains, called aminosils, was investigated by Small-Angle X-ray Scattering (SAXS). It appears that the composites exhibit a two-level structure. The first level consists of well-condensed cubic-like siloxane octamers, with a radius of gyration around 2 angstrom. The second level is formed by the aggregation of these siloxane nanodomains to form larger structures, in which the nanodomains are spatially correlated and separated by the organic pendant chains. Europium doping inhibits the aggregation between siloxane octamers, leading to a less compact second-level structure. This can be explained by the Eu3+ stop coordination close to the external surface of the siloxane nanodomains, as detected by luminescence spectroscopy.