Stefan Hüfner
Photoelectron
Spectroscopy
Principles and Applications
Third Revised and Enlarged Edition
With 461 Figures and 28 Tables
JSJ Springer
Contents
1.
2.
3.
Introduction and Basic Principles
1.1 Historical Development
1.2 T h e Electron Mean Free P a t h
1.3 Photoelectron Spectroscopy
and Inverse Photoelectron Spectroscopy
1.4 Experimental Aspects
1.5 Very High Resolution
l.G The Theory of Photoemission
1.6.1 Gore-Level Photoemission
1.6.2 Valence-State Photoemission
1.6.3 Three-Step and One-Step Considerations
1.7 Dcviations from the Simple Theory of Photoemission
References
1
1
9
14
20
27
39
42
45
50
51
57
Core Levels and Final States
2.1 Core-Levcl Binding Energies in Atoms and Moleculcs
2.1.1 The Equivalent-Core Approximation
2.1.2 Chemical Shifts
2.2 Corc-Lcvel Binding Energies in Solids
2.2.1 The Born Haber Cycle in Insulators
2.2.2 Theory of Binding Energies
2.2.3 Determination of Binding Energies and Chemical Shifts
from Thermodynamic D a t a
2.3 Core Polarization
2.4 Final-State Multiplets in R a r e - E a r t h Valence Bands
2.5 Vibrational Side Bands
2.6 Gore Levels of Adsorbed Molecules
2.7 Quantitative Chemical Analysis from Core-Level Intensities . .
References
61
63
63
65
69
69
71
76
83
92
99
100
103
104
Charge-Excitation Final States: Satellites
3.1 Copper Dihalides; 3d Transition Metal Compounds
3.1.1 Characterization of a Satellite
3.1.2 Analysis of Charge-Transfer Satellites
109
110
110
115
•...
XII
Contents
3.1.3 Non-local Screening
3.2 The 6-eV Satellite in Nickel
3.2.1 Resonance Photoemission
3.2.2 Satellites in Other Metals
3.3 T h e Gunnarsson-Schönhammer Theory
3.4 Photoemission Signals and Narrow Bands in Metals
References
4.
5.
Continuous Satellites and P l a s m o n Satellites:
X P S P h o t o e m i s s i o n in N e a r l y Free E l e c t r o n S y s t e m s
4.1 Theory
4.1.1 General
4.1.2 Core-Line Shape
4.1.3 Intrinsic Plasmons
4.1.4 Extrinsic Electron Scattering:
Plasmons and Background
4.1.5 T h e Total Photoelectron Spectrum
4.2 Experimental Results
4.2.1 T h e Gore Line W i t h o u t Plasmons
4.2.2 Core-Level Spectra Including Plasmons
4.2.3 Valence-Band Spectra of the Simple Metals
4.2.4 Simple Metals: A General Comment
4.3 The Background Correction
References
V a l e n c e O r b i t a l s in S i m p l e M o l e c u l e s
and I n s u l a t i n g S o l i d s
5.1 UPS Spectra of Monatomic Gases
5.2 Photoelectron Spectra of Diatomic Molecules
5.3 Binding Energy of the H2 Molecule
5.4 Hydrides Isoelectronic with Noble Gases
Neon (Ne)
Hydrogen Fluoride (HF)
Water ( H 2 0 )
Ammonia (NH 3 )
Methane (CH 4 )
5.5 Spectra of the Alkali Halides
5.6 Transition Metal Dihalides
5.7 Hydrocarbons
5.7.1 Guidelines for the Interpretation of Spectra
from Free Molecules
5.7.2 Linear Polymers
5.8 Insulating Solids with Valence d Electrons
5.8.1 The NiO Problem
5.8.2 Mott Insulation
126
130
133
143
148
152
166
173
181
181
182
183
185
187
187
187
190
195
200
201
206
211
212
214
221
222
223
223
223
224
224
225
232
233
238
238
244
254
268
Contents
T h e Metal-Insulator Transition; the Ratio
of the Correlation Energy and the Bandwidth; Doping
5.8.4 Band Structures of Transition Metal Compounds . . . .
5.9 High-Temperature Superconductors
5.9.1 Valence-Band Electronic Structure;
Polycrystalline Samples
5.9.2 Dispersion Relations
in High Temperature Superconductors; Single Crystals
5.9.3 Thc Superconducting G a p
5.9.4 Symmetry of the Order P a r a m e t e r
in t h e High-Temperature Superconductors
5.9.5 Core-Level Shifts
5.10 T h e Fermi Liquid and the Luttinger Liquid
5.11 Adsorbed Molecules
5.11.1 Outline
5.11.2 CO on Metal Surfaces
Rcfcrences
XIII
5.8.3
274
283
286
287
303
310
312
315
317
324
324
324
337
P h o t o e m i s s i o n of V a l e n c e E l e c t r o n s
from M e t a l l i c S o l i d s
in t h e O n e - E l e c t r o n A p p r o x i m a t i o n
347
6.1 Theory of Photoemission:
A Summary of the Three-Stcp Model
349
6.2 Discussion of the Photocurrcnt
357
6.2.1 Kinematics of Internal Photoemission
in a Polycrystalline Sample
357
6.2.2 P r i m a r y and Secondary Cones
in the Photoemission from a Real Solid
365
6.2.3 Angle-Integrated and Angle-Resolved D a t a Collection . 366
6.3 Photoemission from the Semi-infinite Crystal:
T h e Inverse L E E D Formalism
374
6.3.1 Band Structure Regime
381
6.3.2 X P S Regime
381
6.3.3 Surface Emission
383
6.3.4 One-Step Calculations
385
6.4 Thermal Effects
387
6.5 Dipole Selection Rules for Direct Optical Transitions
401
References
407
Band Structure
and Angular-Resolved Photoelectron Spectra
7.1 Free-Elcctron Final-State Model
7.2 Methods Employing Calculated Band Structures
7.3 Methods for the Absolute Determination
of the Crystal Momentum
411
413
415
418
XIV
Contents
7.3.1
7.3.2
Triangulation or Energy Coincidence Method
Bragg Plane Method: Variation of External Emission
Angle at Fixed P h o t o n Frcquency
(Disappearance/Appearance Angle Method
7.3.3 Bragg Plane Method: Variation of P h o t o n Energy
at Fixed Emission Angle (Symmetry Method)
7.3.4 T h e Surface Emission Method and Electron Damping
7.3.5 T h e Very-Low-Energy Electron Diffraction Method . .
7.3.6 T h e Fermi Surface Method
7.3.7 Intensities and Their Use
in Band-Structure Determinations
7.3.8 Summary
7.4 Experimental Band Structures
7.4.1 One- and Two-Dimensional Systems
7.4.2 Three-Dimensional Solids: Metals and Semiconductors
7.4.3 UPS Band Structures and X P S Density of States
7.5 A Comment
References
421
445
450
453
453
472
481
493
495
8.
S u r f a c e S t a t e s , S u r f a c e Effects
8.1 Theoretical Considerations
8.2 Experimental Results on Surface States
8.3 Quantum-Well States
8.4 Surface Core-Level Shifts
References
501
503
513
529
535
546
9.
Inverse P h o t o e l e c t r o n Spectroscopy
9.1 Surface States
9.2 Bulk Band Structures
9.3 Adsorbed Molecules
References
551
555
560
563
571
425
433
437
439
443
10. S p i n - P o l a r i z e d P h o t o e l e c t r o n S p e c t r o s c o p y
10.1 General Description
10.2 Exaniples of Spin-Polarized Photoelectron Spectroscopy
10.3 Magnetic Dichroism
References
575
575
575
586
593
11. P h o t o e l e c t r o n Diffraction
11.1 Examples
11.2 Substrate Photoelectron Diffraction
11.3 Adsorbate Photoelectron Diffraction
11.4 Fermi Surface Scans
References
597
601
607
619
626
633
Contents
XV
Appendix
A.l Table of Binding Energies
A.2 Surface and Bulk Brillouin Zones of the Three Low-Index Faces
of a Face-Centered Cubic (fcc) Crystal Face
A.3 Compilation of Work Functions
References
635
636
642
650
651
Index
653
,