Universiẗat, Diss., 1999--Osnabrück.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16874号 / 工博第3595号 / 新制||工||1543(附属図書館) / 29549 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 一義, 教授 佐藤 啓文, 教授 梶 弘典 / 学位規則第4条第1項該当

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Charakterisierung des literarischen Schaffens von Moritz Jahn. Seine Bedeutung für das Plattdeutsche. F. E. Peters beschreibt, Moritz Jahn humorvoll folgend, "polare Spannungen" in Niederdeutschland: "Es gibt Niederdeutsche, die ihrem Lande nie so ganz trauen, die daheim in einer immerwährenden leisen Unruhe hinleben und die aufatmen, wenn sie in gebirgiger Gegend das nackte Gestein unter ihren Füßen fühlen. Dann wird klar, was sie sich bis dahin mühsam verhehlt haben: dass sie nämlich in einem geheimen Winkel ihrer Seele glauben, ihr Land sei vom Meere unterspült, könne an besonders dünnen Stellen durchbrechen, vom festen Kern der Erde losgerissen werden und in die Nebel der Unendlichkeit hinaustreiben. Auf felsigem Grund werden sie dann die neue und wohltuende Sicherheit mit großer Freude so lange genießen, bis das unwiderstehliche Heimweh sie zurücktreibt in die Unsicherheit."

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In this study, we focus on the substituent effect of the diketone ligands on the structural variation of £]- diketonato metal complexes containing N,N-dimethyl formamide (DMF). Three £]-diketones (hfac, bztf, bzbz) were used, and six-, five-, four- coordinated complexes were found accordingly. It is surprising to find that all six metal-oxygen bonds in the M(hfac)2(DMF)2 complexes are of equal length, seemly in violation of Jahn-Teller theorem. Possible reasons for this observation were discussed in this thesis.

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A detailed study is made on the luminescence of Pb('2+) ions in alkali halide single crystals. The emission spectra of KX:Pb('2+) (X = Cl, Br, I) excited in the A-absortpion band at various temperatures are reported. In addition, the excitation spectra of the A-band emission measured at 4.2 and 78 K are also given. The temperature dependence and the effect of an external magnetic field on the decay time of the A-band emission from KX:Pb('2+) is also investigated. / The results are interpreted in terms of a model that includes the Jahn-Teller effect, the spin-orbit interaction and an additional perturbation caused by the charge compensating cation vacancy (CV, v(,c)('-)). In this model, the Jahn-Teller effect is much smaller than the spin-orbit interaction and the CV is smaller still. The experimental results for KX:Pb('2+) are well in accord with this model. / The angular dependence of the polarization of the A-band emission from KX:Pb('2+) confirms that the Pb('2+) - v(,c)('-) pair is located on the C(,4) crystallographic axis. The temperature dependence of the polarization is treated within the framework of the above model in terms of the nonradiative processes between the relaxed excited states.

The resurgence of interest in properties of molecules of icosahedral symmetry follows the discovery of the C₆₀ molecule. Due to the high symmetry of the icosahedron, almost all the electronic and vibrational levels are highly degenerate, so that in dealing with properties of these systems, the Jahn-Teller interaction must almost always be allowed for. This thesis primarily explores the properties of the icosahedral G ⊗ (g ⊕ h] interaction and related subsystems in the strong coupling régime. Mappings of the adiabatic potential energy surfaces facilitate an analysis of the geometrical phase or Berry phase acquired by the quantal system on transportation around adiabatic circuits in parameter space. The Berry phase information in conjunction with an analysis of tunnelling, determines the properties of the ground state. The use of Ham factors achieves a characterization of the various coupling régimes. However, characterization of G and H Jahn-Teller systems, requires an extension of the standard definition of these Ham factors. In such cases the extended matrix elements between and within vibronic tunnelling sublevels cannot be ignored. A calculation of all the standard and extended matrix elements is presented. A further introduction of a matrix of Ham factors facilitates the description of H multiplicity within an H manifold. Finally, two problems are investigated numerically; aimed at making some allusion towards possible experimental manifestations of G ⊗(g(⊕)h). The first investigation considers the variations in the eigensystem and Ham factors of G ⊗ (g ⊕ h), as a function of the coupling to the two modes. The second investigation considers the structure in the optical absorption line shapes for the transitions from orbital singlet to quartet, G, states in an icosahedral environment. The quartet states are subject to both spin-orbit and linear Jahn-Teller interactions.