Preface ...................................................... XIII
List of Acronyms ............................................. XVII
1. Introduction ................................................ 1
1.1. Heterogeneous Catalysis ............................... 1
1.2. The Aim of Catalyst Characterization .................. 4
1.3. Spectroscopic Techniques .............................. 5
1.4. Research Strategies ................................... 7
References ...................................................... 9
2. Temperature-Programmed Techniques .......................... 11
2.1. Introduction ......................................... 11
2.2. Temperature-Programmed Reduction ..................... 13
2.2.1. Thermodynamics of Reduction .................. 13
2.2.2. Reduction Mechanisms ......................... 15
2.2.3. Applications ................................. 18
2.3. Temperature-Programmed Sulfidation ................... 21
2.4. Temperature-Programmed Reaction Spectroscopy ......... 22
2.5. Temperature-Programmed Desorption .................... 23
2.5.1. TPD Analysis ................................. 29
2.5.2. Desorption in the Transition State Theory .... 31
2.6. Temperature-Programmed Reaction Spectroscopy
in UHV ............................................... 35
References ................................................. 37
3. Photoemission and Auger Spectroscopy ....................... 39
3.1. Introduction ......................................... 39
3.2. X-Ray Photoelectron Spectroscopy (XPS) ............... 41
3.2.1. XPS Intensities and Sample Composition ....... 44
3.2.2. XPS Binding Energies and Oxidation States .... 46
3.2.3. Shake Up, Shake Off, Multiplet Splitting
and Plasmon Excitations ...................... 50
3.2.4. Experimental Aspects of XPS .................. 51
3.2.5. Charging and Sample Damage ................... 52
3.2.6. Dispersion of Supported Particles from XPS ... 54
3.2.7. Angle-Dependent XPS .......................... 59
3.2.8. In-Situ and Real Time XPS Studies ............ 63
3.3. Ultraviolet Photoelectron Spectroscopy (UPS) ......... 65
3.3.1. Photoemission of Adsorbed Xenon .............. 71
3.4. Auger Electron Spectroscopy .......................... 74
3.4.1.Energy of Auger Peaks .......................... 75
3.4.2. Intensity of Auger Peaks ..................... 77
3.4.3. Application of AES in Catalytic Surface
Science ...................................... 78
3.4.4. Scanning Auger Spectroscopy .................. 80
3.4.5. Depth-Sensitive Information from AES ......... 80
References ................................................. 81
4. The Ion Spectroscopies ..................................... 85
4.1. Introduction ......................................... 85
4.2. Secondary Ion Mass Spectrometry (SIMS) ............... 86
4.2.1. Theory of SIMS ............................... 88
4.2.2. Electron and Photon Emission under Ion
Bombardment .................................. 90
4.2.3. Energy Distribution of Secondary Ions ........ 91
4.2.4. The Ionization Probability ................... 92
4.2.5. Emission of Molecular Clusters ............... 94
4.2.6. Conditions for Static SIMS ................... 94
4.2.7. Charging of Insulating Samples ............... 95
4.2.8. Applications on Catalysts .................... 95
4.2.9. Model Catalysts .............................. 99
4.2.10. Single Crystal Studies ...................... 101
4.2.11. Concluding Remarks .......................... 105
4.3. Secondary Neutral Mass Spectrometry (SNMS) .......... 105
4.4. Ion Scattering: The Collision Process ............... 106
4.5. Rutherford Backscattering Spectrometry (RBS) ........ 108
4.6. Low-Energy Ion Scattering (LEIS) .................... 112
4.6.1. Neutralization .............................. 113
4.6.2. Applications of LEIS in Catalysis ........... 114
References ................................................ 117
5. Mössbauer Spectroscopy .................................... 121
5.1. Introduction ........................................ 121
5.2. The Mössbauer Effect ................................ 122
5.3. Mössbauer Spectroscopy .............................. 126
5.3.1. Isomer Shift ................................ 128
5.3.2. Electric Quadrupole Splitting ............... 129
5.3.3. Magnetic Hyperflne Splitting ................ 131
5.3.4. Intensity ................................... 132
5.4. Mössbauer Spectroscopy in Catalyst
Characterization .................................... 134
5.4.1. In-Situ Mössbauer Spectroscopy at
Cryogenic Temperatures ...................... 137
5.4.2. Particle Size Determination ................. 139
5.4.3. Kinetics of Solid-State Reactions from
Single Velocity Experiments ................. 140
5.4.4. In-Situ Mössbauer Spectroscopy Under
Reaction Conditions ......................... 141
5.4.5. Mössbauer Spectroscopy of Elements Other
Than Iron ................................... 143
5.5. Conclusion .......................................... 145
References ................................................ 145
6. Diffraction and Extended X-Ray Absorption Fine Structure
(EXAFS) ................................................... 147
6.1. Introduction ........................................ 147
6.2. X-Ray Diffraction ................................... 148
6.2.1. In-Situ XRD: Kinetics of Solid-State
Reactions ................................... 152
6.2.2. Concluding Remarks .......................... 154
6.3. Low-Energy Electron Diffraction (LEED) .............. 155
6.4. X-Ray Absorption Fine Structure (XAFS) .............. 159
6.4.1. EXAFS ....................................... 160
6.4.2. Quick EXAFS for Time-Resolved Studies ....... 170
6.4.3. X-Ray Absorption Near Edge Spectroscopy ..... 172
References ................................................ 175
7. Microscopy and Imaging .................................... 179
7.1. Introduction ........................................ 179
7.2. Electron Microscopy ................................. 180
7.2.1. Transmission Electron Microscopy ............ 182
7.2.2. Scanning Electron Microscopy ................ 184
7.2.3. Scanning Transmission Electron Microscopy ... 186
7.2.4. Element Analysis in the Electron
Microscope .................................. 190
7.3. Field Emission Microscopy and Ion Microscopy ........ 193
7.3.1. Theory of FEM and FIM ....................... 193
7.4. Scanning Probe Microscopy: AFM and STM .............. 197
7.4.1. AFM and SFM ................................. 198
7.4.1.1. Contact Mode AFM .................. 199
7.4.1.2. Non-Contact Mode AFM .............. 200
7.4.1.3. Tapping Mode AFM .................. 200
7.4.2. AFM Equipment ............................... 200
7.4.3. Scanning Tunneling Microscopy (STM) ......... 205
7.4.4. Applications of STM in Catalytic
Surface Science ............................. 208
7.5. Other Imaging Techniques ............................ 211
7.5.1. Low-Energy Electron Microscopy and
Photoemission Electron Microscopy ........... 212
References ................................................ 214
8. Vibrational Spectroscopy .................................. 217
8.1. Introduction ........................................ 217
8.2. Theory of Molecular Vibrations ...................... 218
8.3. Infrared Spectroscopy ............................... 224
8.3.1. Equipment ................................... 226
8.3.2. Applications of Infrared Spectroscopy ....... 226
8.3.3. Transmission Infrared Spectroscopy .......... 227
8.3.4. Diffuse Reflectance Infrared Fourier
Transform Spectroscopy (DRIFTS) ............. 230
8.3.5. Attenuated Total Reflection ................. 233
8.3.6. Reflection Absorption Infrared
Spectroscopy (RAIRS) ........................ 234
8.4. Sum-Frequency Generation ............................ 235
8.5. Raman Spectroscopy .................................. 238
8.5.1. Applications of Raman Spectroscopy .......... 240
8.6. Electron Energy Loss Spectroscopy (EELS) ............ 243
8.7. Concluding Remarks .................................. 247
References ................................................ 248
9. Case Studies in Catalyst Characterization ................. 251
9.1. Introduction ........................................ 251
9.2. Supported Rhodium Catalysts ......................... 251
9.2.1. Preparation of Alumina-Supported Rhodium
Model Catalysts ............................. 252
9.2.2. Reduction of Supported Rhodium Catalysts .... 254
9.2.3. Structure of Supported Rhodium Catalysts .... 257
9.2.4. Disintegration of Rhodium Particles
Under CO .................................... 261
9.2.5. Concluding Remarks .......................... 264
9.3. Alkali Promoters on Metal Surfaces .................. 264
9.4. Cobalt-Molybdenum Sulfide Hydrodesulfurization
Catalysts ........................................... 272
9.4.1. Sulfidation of Oxidic Catalysts ............. 272
9.4.2. Structure of Sulfided Catalysts ............. 276
9.5. Chromium Polymerization Catalysts ................... 284
9.6. Concluding Remarks .................................. 292
References ................................................ 293
Appendix. Metal Surfaces and Chemisorption .................... 297
A.1. Introduction ............................................. 297
A.2. Theory of Metal Surfaces ................................. 297
A.2.1. Surface Crystallography ........................... 297
A.2.2. Surface Free Energy ............................... 301
A.2.3. Lattice Vibrations ................................ 302
A.2.4. Electronic Structure of Metal Surfaces ............ 305
A.2.5. Work Function ..................................... 309
A.3. Chemisorption on Metals .................................. 311
A.3.1. Adsorption of Molecules on Jellium ................ 315
A.3.2. Adsorption on Metals with d-Electrons ............. 317
A.3.3. Concluding Remarks ................................ 319
References .................................................... 319
Index ......................................................... 321
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