FU Berlin Digitale Dissertation
Ralph Wichtendahl : Instrumentation for BESSY II and temperature programmed desorption of CO, NO and water of the (100)-single crystal cleavage planes of the metal oxides NiO and MgO Instrumentierung für BESSY II und temperaturprogrammierte Desorption von CO, NO und Wasser von (100)-Einkristallspaltflächen der Metalloxide NiO und MgO
|Abstract| |Table of Contents| |More Information|

Abstract For the spectromicroscope SMART, an independent preparation chamber and a vibration isolation system accurate to 2 mm in spite of lateral forces have been set up. Placed in a row with the SMART at BESSY, a spectrometer system has been built. It contains a high-resolution energy analyser, a partial-yield- and a fluorescence detector, sample preparation tools and helium cooling. XPS investigations on tantalum deposits on Al2O3/NiAl(110) thin films revealed that submonolayer deposits show no oxidation although thicker films do. For the first time, temperature programmed desorption (TPD, TDS) of CO, NO, and H2O has been investigated including the respective multilayer desorptions on UHV-cleaved single crystal MgO and NiO-surfaces. The following desorption energies can be assigned to the desorption from regular sites on the surface for small coverages, in the case of NiO contradicting the theoretical expectations: CO NO H2O MgO(100) 0.14 eV 0.22 eV 0.66 eV NiO(100) 0.30 eV 0.57 eV 0.59 eV With regard to these desorptions, the thin NiO(100)/Ni(100)-film is equivalent to the single crystal cleavage plane. Up to 125 K, a CO-c(4x2)-superstructure is measured by means of MCP-LEED. Only CO/NiO(100) shows a decrease of the desorption peak temperature with increasing coverage. Thus, a substrate-induced or substrate-mediated repulsive lateral interaction of the adsorbed CO is concluded. An upright adsorption geometry is calculated for NO/MgO(100). The differences with respect to NO/NiO(100) are attributed to the lack of Mg-3d-electrons, though a covalent contribution to the binding is missing. Water desorbs from both substrates at 197 K from a superstructure which is suggested for NiO, too.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title 1 Eine Einleitung: Metalloxide 11 I Grundlagen 21 2 TPD 23 3 Hartree-Fock-Theorie 31 4 Spektroskopie im mikroskopischen Maßstab 35 II Aufbauten 41 5 Experimentiersystem für Oberfächenanalytik 43 6 Monochromator PM-6 47 7 Spektrometer 53 8 SMART 69 9 Laborapparatur 79 10 Allgemeine Komponenten 81 III Spektrometermessungen 95 11 Oxidationsverhalten von Tantalaggregaten 97 IV Physisorbate auf Metalloxiden: CO, NO und H2O auf MgO und NiO 101 12 Probenaufbau 103 13 Literaturübersicht 107 14 Messungen 119 15 Zusammenfassung 147 Literaturverzeichnis 151

More Information:
Online available:	http://www.diss.fu-berlin.de/1999/56/indexe.html
Language of PhDThesis:	german
Keywords:	TPD, XPS, binding energy, NiO(100), MgO(100), single crystal
DNB-Sachgruppe:	29 Physik, Astronomie
Classification PACS:	68.45.De und 07.85.Qe
Date of disputation:	01-Jul-1999
PhDThesis from:	Fachbereich Physik, Freie Universität Berlin
First Referee:	Prof. Dr. Hans-Joachim Freund
Second Referee:	Prof. Dr. Klaus Christmann
Contact (Author):	ralph.wichtendahl@infineon.com
Contact (Advisor):	freund@fhi-berlin.mpg.de
Date created:	06-Oct-1999
Date available:	24-Aug-2000

 

---

|| DARWIN|| Digitale Dissertationen || Dissertation|| German Version|| FU Berlin|| Seitenanfang ||

---

	Fragen und Kommentare an: darwin@inf.fu-berlin.de
© Freie Universität Berlin 1999