Resumen de Surface and interface effects in NiO
INDEX INTRODUCTION"3 EXPERIMENTAL TECHNIQUES II.1. X-RAY PHOTOEMISSION SPECTROSCOPY (XPS).............................................13 II.1.1 X-Ray Photoemission Spectroscopy (XPS) Fundamentals..................................13 II.1.2 Analytical physics of XPS....................................................................................13 II.1.3 Energy Calibration............................................................................19 II.1.4 Quantitative Analysis...........................................................................................20 II.1.5. System Component Overview.............................................................................21 II.1.6. Quantitative Analysis of Surfaces by Electron Spectroscopy (QUASES)...........22 II.1.6.1 Concept of the QUASES analysis procedures............................................23 II.1.6.2 Quantification with Peak Intensities...........................................................24 II.1.6.3 Quantification with QUASES......................................................................27 II.1.6.4. Inelastic electron scattering cross sections...............................................29 II.1.7. HArd X-Ray PhotoEmission Spectroscopy (HAXPES).....................................31 II.2 X-RAY ABSORPTION SPECTROSCOPY................................................................34 II.2.1 X-ray Absorption Spectroscopy, edges................................................................34 II.2.2. Extended X-ray Absorption Fine Structure........................................................35 II.2.3. X-ray absorption coefficient vs. photon energy..................................................40 II.2.4. Computational procedure in NEXAFS...............................................................43 II.2.5. Low energy absorption spectroscopy (XAS).......................................................47 II.2.5.1. Unoccupied Density of States Aproach......................................................47 II.2.5.2. Multiplet Theory Approach........................................................................49 II.3. ATOMIC FORCE MICROSCOPY.............................................................................52 REFERENCES........................................................................57 iii EXPERIMENTAL DETAILS III.1. INTRODUCTION........................................................................61 III.2. SAMPLE PREPARATION......................................................................62 III.2.1. Strategy of the study...........................................................................................62 III.2.2. NiO Growth.................................................................................63 III.2.3. Nanostructured NiO Growth.............................................................................65 III.2.4. Graphite cleaning process.................................................................................67 III.2.5. Oxide Substrates preparation............................................................................69 III.3. EXPERIMENTAL SYSTEMS FOR MEASUREMENTS.........................................73 III.3.1. In-house XPS Spectrometer...............................................................................73 III.3.2. PES-XAS measurements at BESSY II.................................................................75 III.3.3. NEXAFS measurements at ESRF and BESSY II................................................77 III.3.4. HAXPES measurements at ESRF.......................................................................79 III.3.5. AFM Imaging.......................................................................80 REFERENCES:....................................................................81 SURFACE EFFECTS in NiO IV.1. INTRODUCTION....................................................................85 IV.2. MORPHOLOGICAL STUDY OF THE GROWTH OF NiO ON HOPG.................86 IV.2.1. QUANTITATIVE ANALYSIS BY MEANS OF XPS INELASTIC PEAK SHAPE (QUASES).........................................................................87 IV.2.2. STUDY OF THE GROWTH OF NiO ON HOPG BY AFM...............................90 IV.2.3. COMPARISON QUASES"AFM.......................................................................102 IV.3. SURFACE EFFECTS IN NiO..................................................................................103 IV.3.1. STUDY OF THE GROWTH OF NiO ON HOPG BY XAS...............................104 IV.3.2. SURFACE EFFECTS IN Ni 2p XPS SPECTRA..............................................112 IV.3.3. STUDY OF THE SURFACE EFFECTS IN NiO BY HAXPES.........................122 IV.3.4. STUDY OF THE GROWTH OF NiO ON HOPG BY XPS...............................128 CONCLUSIONS..........................................................................134 REFERENCES.............................................................................135 iv INTERFACE EFFECTS IN NiO/OXIDES V.1 INTRODUCTION......................................................................139 V.2. MORPHOLOGICAL STUDY OF THE GROWTH OF NiO ON OXIDES............141 V.2.1. QUANTITATIVE ANALYSIS BY MEANS OF XPS INELASTIC PEAK SHAPE".141 V.2.2. QUASES RESULTS FOR GROWTH OF NiO ON OXIDES.............................146 V.2.3. NiO/SiO2 AFM STUDY.....................................................................................149 V.3. STUDY OF THE GROWTH OF NiO/OXIDES BY XPS........................................152 V.3.1. THE FINAL AND EARLY STAGES OF GROWTH..........................................158 V.3.2 CLUSTER MODEL CALCULATION................................................................161 V.3.3. THROUGH THE GROWTH PROCESS...........................................................165 V.4. STUDY OF THE GROWTH OF NiO/OXIDES BY NEXAFS................................170 V.4.1. EXPERIMENTAL SPECTRA............................................................................171 V.4.2. EXPLORING CLUSTER SIZE AND EXCHANGE AND CORELATION POTENTIALS................................................................................172 V.4.3. EXPLORING INTERFACE EFFECTS.............................................................177 CONCLUSIONS..................................................................189 REFERENCES............................................................................189 APLICATION"191 CONCLUSIONS"197 APPENDIX".201 TABLE AND FIGURE INDEX.......................................................................................221 LIST OF PUBLICATIONS v
