The aim of the present work was to develop a detailed picture of the electronic and magnetic properties of a number of interesting transition metal compounds. A number of complementary experimental and theoretical techniques have been applied, special emphasis was given to x-ray spectroscopies. The studies led to a number of results, and the following conclusions can be drawn: The influence of the magnetic ground state (high-spin (FeO) vs. low-spin (FeS2)) with respect to the recorded x-ray spectra was investigated. In particular, by performing RXES on the Fe L edge of the two compounds, very different ratios of La / Lβ integrated intensity for excitation energies close to the L2 edge have been observed. This effect has been explained in terms of the magnetic structure of FeO (high spin), which inhibits Coster-Kronig processes. Special attention has been given to the direct investigation of orbital ordering in a three dimensional CMR manganite, namely La7/8Sr1/8MnO3, by means of x-ray linear dichroism (XLD). We obtained, for the first time, rather strong indications that the coherently distorted Jahn-Teller phase in La7/8Sr1/8MnO3 is accompanied by a predominantly cross type (x2-z2) / (y2-z2) orbital ordering. In addition to manganites the double perovskite Sr2FeMoO6 the combined study by means of x-ray spectroscopies, magnetic measurements and theoretical band structure calculations could resolve some points discussed controversially in the literature. Both, paramagnetic measurements as well as core level spectroscopy of the Fe 2p, Fe 3s and the Mo 3d states suggest a mixed iron valence state involving around 30% Fe3+- Mo5+ and 70% Fe2+ - Mo6+ states in highly ordered Sr2FeMoO6. XPS valence band studies reveal that the Fe 3d states are not extremely localized, and we find evidence that charge transfer between Fe 3d and O 2p states plays an essential role.

Diese Dissertationsschrift ist angesiedelt im Bereich Digitaler Edition archivalischer Quellen, deren Erschließung und (computergestützter) Analyse. Im Zentrum stehen die sog. Kosmos-Vorträge, die Alexander von Humboldts 1827/28 in zwei Vortragszyklen in Berlin gehalten hat. Diese werden als gleichwertige, zweifache Publikationen in Humboldts Werkbiographie eingeordnet. In einem zentralen Kapitel (Kap. 7) geht es mir um eine editionstheoretische Fundierung der Edition von Vorlesungsnachschriften, zunächst allgemein und dann bezogen auf die Nachschriften der Kosmos-Vorträge. Zuvor wird das Forschungsfeld beleuchtet, da über die Rahmenbedingungen und Inhalte der beiden Vortragsreihen bislang nur wenig bekannt war. Humboldts Motivation zu diesen Vorträgen, deren Zusammenhang mit dem Kosmos (1845–62) und weiteren seiner Publikationen, sowie die jeweiligen organisatorischen Rahmenbedingungen werden untersucht. Inhaltlich sind die Kosmos-Vorträge bislang wenig erforscht worden, unter anderem weil die wichtigsten Quellen nicht rezipiert wurden. Dank der Digitalisierung des Humboldt-Nachlasses und vor allem durch die Digitale Edition der Nachschriften aus dem Hörerkreis sind die Voraussetzungen dafür mittlerweile sehr viel besser. Um die künftige Arbeit mit diesen Dokumenten zu unterstützen, dokumentiere und reflektiere ich in Kapitel 8 die praktische Umsetzung des Editionsmodells gemäß den Richtlinien der Text Encoding Initiative (TEI). Anschließend stelle ich die edierten Nachschriften aus beiden Vortragszyklen vor und zeige, wie sich mit den digitalen Volltexten arbeiten lässt. Dabei kommen quantitative Untersuchungen und Verfahren wie automatische Kollation bzw. Plagiatssuche, aber auch ‚traditionell hermeneutische‘ Methoden zum Einsatz. Schließlich geht es mir in meiner Arbeit darum, die Grundlage für die weitere Erforschung der beiden Vortragsreihen wesentlich zu verbessern und anhand einiger exemplarischer Analysen erste Schritte in diese Richtung zu unternehmen. / This dissertation is located in the field of digital editions of archival sources, their exploration and (computer-assisted) analysis. In terms of content, it deals with the so-called Kosmos-Lectures, which Alexander von Humboldt held in two distinct courses in Berlin in the winter of 1827/28. The two series are recognised as two distinct publications of equal value in Humboldt’s oeuvre. In a central chapter (chapter 7), I am concerned with an edition-theoretical foundation for the edition of attendee’s notebooks, first in general and then in relation to the transcripts of the Kosmos-Lectures. Before this, the research field of the long-neglected Kosmos-Lectures is illuminated, as little has been known about the framework conditions of the lecture series. Humboldt’s motivation for these lectures, their connection with the Kosmos (1845–62) and other of his publications, and the respective organisational framework of the courses are being examined. In terms of content, the Kosmos-Lectures have so far been little researched, partly because the most important sources have not been taken into consideration. The conditions for this are now much better thanks to the digitisation of the Humboldt legacy collection and, above all, the digital edition of the transcripts from the audience. To facilitate future work with these documents, I document and reflect the practical implementation of the edition model according to the Text Encoding Initiative (TEI) in chapter 8. In the following two chapters, I present the attendee’s notebooks from both courses, and show how to work with these digital full texts. Quantitative investigations and methods such as automatic collation or text re-use detection, but also ‘traditional hermeneutic’ approaches are used. Ultimately, my work aims to significantly improve the basis for research into the two lecture series, which has so far been lacking, and to take the first steps in this direction by means of some exemplary analyses.

In this work the electronic and magnetic structure of the crystals Sr2FeMoO6, Fe0.5Cu0.5Cr2S4, LuFe2O4 and the molecules FeStar, Mo72Fe30, W72Fe30 are investigated by means of X-ray spectroscopic techniques. These advanced materials exhibit very interesting properties like magnetoresistance or multiferroic behaviour. In case of the molecules they also could be used as spin model systems. A long standing issue concerning the investigation of these materials are contradicting results found for the magnetic and electronic state of the iron (Fe) ions present in these compounds. Therefore this work focuses on the Fe state of these materials in order to elucidate reasons for these problems. Thereby the experimental results are compared to multiplet simulations.