We report a new set oftheoretical transition probabilities in Y II, obtained using a multiconfiguration relativistic Hartree-Fock method including core polarization. The overall quality of the calculations is assessed by comparisons with new and previous lifetime measurements. In this paper, we report new measurements of five lifetimes in the 4d5p and 5s5p configurations, in the energy range of 32 048-44 569 cm −1 , obtained by the time-resolved laser-induced fluorescence method. A similar theoretical model, applied to Y III, leads to results in good agreement with new laser measurements of two 5p levels obtained in this work and with previous beam-foil results for 5d and 6s levels. An extensive set of oscillator strengths is also proposed for Y III.
Binary triglyceride systems containing palmitic, stearic, and oleicMolekulare Verbindongen bildende Mdyceddiyrteme of systems: 2-oleoyl-disaturatedl-oleoyl-disaturated and 2-oleoyl-gen im Verbilltois 1: 1 wurden in zwei unterschiedlichen Systemen nachgewiesen: 2-01eoy1-digesilttigt/I-Oleoyl-digesgttigt und 2-OleoYl-digeslttigtf2-geslttigt-Dioleoyl. Die allgemeine Kristallstruktur im fesolid state are proposed for the systems and according to this different sten Zustand fur diese Systeme wird vorgeschlagen. Die unterschiedli-disaturated/2-saturated-di~leoyl. me general packing principles in the chain packings exist in different layers within the same crystal form. Diffraction pattern versus temperature shows an enhanced polymorphic transition to the 1:l-compound. In diffraction pattern versus time measurements, above the melting point of the a-form, the crystallization process goes directly to the @-form, but, according to experimental results, the 8'-form exists as a transition state. I n t r o d u c t i o nTko relevant reviews on fat polymorphism have been reported. Thus, Rossef' collected the phase diagram of triglyceride systems published up to the end of 1965, and T i m 2 has discussed the phase behaviour of fats and their mixtures. Both authors pointed out, that in certain mixtures of binary triglyceride systems, unexpected melting behaviour is due to compound formation. In these systems the components have both saturated and unsaturated hydrocarbon chains linked to the glycerol residue. The compound is the result of favourable molecular packing of the fatty acid chains. This kind of chain interaction is interesting, because in a mixture of two glycerides with different stable polymorphs the interaction may create a single new stable polymorph.The melting point curve for the system 1,3-di-stearoyl-2-oleoyl glycerol (StOSt)/l,2-di-stearoyl-3-oleoyl glycerol (StStO), carried out by Freeman', was the first indication of compound formation between triglycerides. In an infrared spectroscopic characterization of glycerides by Chapman', it was found that mixtures of equal amount of StOStlStStO give rise to a spectrum quite different from that of either glyceride.In the present study several binary triglyceride mixtures containing palmitic, stearic, and oleic acids were examined by X-ray powder diffraction and differential scanning calorimetry (DSC). The attention has been focused on compound formation. Phase diagrams and polymorphic transitions have been studied with a camera designed for diffraction pattern versus temperature or time (DPT) measurements. The general packing principles of the stable polymorphs were proposed from X-ray powder data, using single crystal structural information from simple saturated triglycerides, oleic acid, and stearic acid. S-43183 Mblndal, Sweden. Fat Sci.Tw41ol. % . $ d U g M S Nr.5 1992 chen Kristallstrukturen der Fettsluresei&ketten liegen in verschiedenen Schichten in der gleichen Kristallform vor. Das Beugungsmuster bei unterschiedlichen Temperaturen zeigt einen verstlrkten pol...
An experimental and theoretical study of the lifetimes of the 3s4p 3P levels in S V and C1 VI is reported. Using the beam-foil technique and extensive cascade corrections with the ANDC method we obtain the following lifetimes in ns: 0.72 f 0.07 ( 3Pz) and 0.37 i. 0.04 ( 3 P , ) in S V, whereas both levels have the same lifetime, 0.24 * 0.03 ns, in C1 VI. The theoretical analysis shows that the large lifetime difference in S V results from a mixing of the 3s4p IP, and 3P, levels, which is enhanced by interactions between the 3s4p and 3p 3d configurations. Calculated transition probabilities for the individual decay channels from the 3s4p 3P levels are also given. In addition, the theoretical analysis indicates an erroneous identification of the 3p 3d 'P and 'F levels in S V.
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