Universiẗat, FB Chemie, Diss.--Hamburg, 2004. / Literaturverz. S. 160 - 167. Zsfassung in engl. Sprache.

Thesis (M.S.)--Ohio State University, 1977. / Includes bibliographical references (leaves 93-97). Available online via OhioLINK's ETD Center

From D.W. Stewart's Thesis (Ph. D.)--University of Michigan, 1939. / "Reprinted from the Physical review, volume 56 ... October 1, 1939."

From D.W. Stewart's Thesis (Ph. D.)--University of Michigan, 1939. / "Reprinted from the Physical review, volume 56 ... October 1, 1939."

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 147-150).

M.Sc. / This dissertation presents experimental data on the near Fermi-level electronic structure of Sr₄Ru₃O₁₀. This summary gives a review of the facts that have been observed in the analysis of the data taken, and directions for future work are suggested. The first part of this dissertation (from chapter 1 to chapter 3) is dedicated to a review on the studied system and the experimental technique exploited in this study. In fact, chapter 1 gives a review of the general physical properties of different members of the Ruddlesden Popper strontium ruthenate family Srn+1RunO3n+1, focusing on the trilayered Sr4Ru3O10 in particular. Furthermore, chapters 2 and 3 discuss some essential features of the theoretical and experimental aspects of angle resolved photoemission spectroscopy (ARPES), respectively. In the second part of the dissertation (chapter 4), the fi rst experimental ARPES data on band dispersions and Fermi surface maps of Sr4Ru3O10, are presented and discussed. The experiment was performed at the beamline Cassiopee of the Soleil synchrotron radiation facility in Paris (France). The study has provided the first information on the near Fermi-level band dispersions and Fermi surface of Sr4Ru3O10, the effect of changing different matrix elements on electronic band dispersions and Fermi surface maps of Sr4Ru3O10, and electronic correlations effects present in this compound. Remarkably, low temperature ( 5 K) ARPES data presented in this study suggest that there is only a 45 rotation of the square unit cell of Sr4Ru3O10, due to correlated rotations about the c-axis of the RuO6 octahedra, but no elongation of the sides of this unit cell; and consequently in reciprocal space the square BZ, determined by considering the symmetry of the Fermi surface sheets, is only rotated by 45 but its size is unchanged with respect to the non-distorted situation. However, this is not what is expected. Using room temperature lattice parameters from ref. [17], the BZ of this compound would be 45 rotated and reconstructed into a square twice smaller, a situation that was also previously observed in band structure calculations and ARPES data of Sr3Ru2O7 from ref. [4]. This behaviour was ascribed to the fact that the structure of this system is possibly not the same at room temperature as at low temperatures (down to 5 K), where the ARPES data of this work were acquired. Therefore low temperature (<100 K) X-ray diffraction data of Sr4Ru3O10 are needed in order to determine low temperature lattice parameters and compare them with room temperature ones so as to verify whether the structure of Sr4Ru3O10 is not the same at room and low temperatures.

The infrared absorption spectra of single crystals of strontium formate and strontium formate dihydrate have been recorded between 4000 and 500 cm⁻¹. Crystal slices cut perpendicular to the crystal axes were employed; the spectra were recorded using polarized radiation, the electric vector being parallel to the direction defined by the crystal axis in question. For Sr(CHO₂)₂it was possible to assign 20 of the 36 infrared active internal fundamentals. In addition lattice modes at: 10, 12, 15, 20, 23, 70, 155, 180 and 200 cm⁻¹ were infered from combinations with internal fundamentals. For Sr(CHO₂)₂.2H₂O it was possible to observe only 10 of the 36 internal fundamentals associated with the formate ions as the absorbing species. Of the 18 internal fundamentals associated with the water molecules as the absorbing species only one mode could be unambiguously assigned. Lattice modes at: 642, 710, 750, 797, 840, 856 and 872 cm⁻¹ were observed and two additional lattice modes at 18 and 110 cm⁻¹ were infered from combinations with internal fundamentals. From the intensity ratios of the internal fundamentals of Sr(CHO₂)₂ it was possible to calculate the direction cosines associated with each of the two crystallographically non-equivalent formate ions contained in the unit cell. / Science, Faculty of / Chemistry, Department of / Graduate

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