Synopses & Reviews
Spectroscopy is a versatile tool for the characterization of materials, and photons in the visible frequency range of the electromagnetic
spectrum have been used successfully for more than a century now. But other elementary particles such as neutrons, muons and x-ray
photons have been proven to be useful probes as well and are routinely generated in modern cyclotrons and synchrotrons. They offer attractive
alternative ways of probing condensed matter in order to better understand its properties and to correlate material behavior with its structure. In particular, the combination of these different spectroscopic probes yields rich information on the material samples, thereby allowing for a systematic investigation down to atomic resolutions.
This book gives a practical account of how well they complement each other for 21st century material characterization, and provides the
basis for a detailed understanding of the scattering processes and the knowledge of the relevant microscopic interactions necessary for the
correct interpretation of the experimentally obtained spectroscopic data.
Aiming elementary particles at surfaces and observing the result in order to glean information on the material is an old discipline: spectroscopy using photons has been performed for more than a century. But recently, a number of much more exotic, subatomic particles such as neutrons, muons or x-rays have been generated in modern cyclotrons and synchrotrons, and due to the steadily growing availability of measurement capacitythey have become attractive as alternative ways of probing condensed matter in order to better understand its properties and to correlate material behaviour with its structure.
In particular, the combined use of several different types of particles such as x-rays, neutrons and muons yields rich information. This book gives a practical account of how well they complement each other for 21st century materials characterization.
About the Author
Walter E. Fischer
(1939-2008) was the former head of the Department of Condensed Matter Research with Neutrons and Muons (NUM) at the Paul Scherrer Institute (PSI) in Villigen, Switzerland. He pioneered in establishing the spallation neutron source SINQ at PSI which went into operation in the mid-1990s. Later he foundes a condensed matter theory group to complement the experimental work at the neutron source.
Rudolf Morf studied at the University of Basel, Switzerland, and did his PhD in Theoretical Physics in the field of nucleon scattering. After postdoc positions at the IBM Research Laboratory in Rüschlikon and at the Harvard University he worked, from 1981 on, at the Research Laboratory of the Radio Corporation of America in Zurich. Since 1987 he heads the Condensed Matter Theory Group of the Paul Scherrer Institute.
Table of Contents
Some Historical Remarks
The Experimental Methods
The Solid as a Many Body System
Survey over the Spectral Region of a Solid
2. THE PROBES, THEIR ORIGIN AND PROPERTIES
Origin: The Photon, the Electron, the Muon, the Neutron
Properties: Electrons, Muons, Neutrons, Photons
Magnetic Field of the Probing Particles
3. INTERACTION OF THE PROBES WITH THE CONSTITUENTS OF MATTER
The Nuclear Interaction of Neutrons: Interaction with Free Nuclei, Bound Scattering Length, Spin and Isospin Considerations
Interaction of X-Rays with Atomic Constituents: Interaction of a Point Charge with an Electromagnetic Field, Scattering of Light at Atomic Constituents, Photoemission
Magnetic Interaction: Neutrons and Muons as Probes, X-Rays as Probes
Corollar: Neutrons, X-rays, Magnetic Interaction
4. SCATTERING ON (BULK-)SAMPLES
The Sample as a Thermodynamic System: Hamiltonian, Partitioning into Subsystems, Interaction of the Probe with the Subsystem
The Scattering Experiment: Differential Cross-Section and the Dynamical Scattering Function, Coherent and Incoherent Scattering, Correlation Functions, Elastic and Inclusive Scattering, Inelastic Scattering
Properties of the Scattering- and Correlation-Function: Mass- and Charge-Densities as Observables, Electronic Currents and Magnetization as Observables
General Form of Spin-Dependent Cross Sections: Introduction, Neutrons, X-rays (non-resonant), Cross-Sections, Spectroscopy
Summary and Conclusions
5. GENERAL THEORETICAL FRAMEWORK
Time Development of the Density Operator: Scattering Function and Cross Section, Wangsness-Bloch Equations ? Relaxation Times (an Application for mu-SR)
Generalized Suspectibility: Electromagnetic Field in a Medium, Green?s Function, Retarded Kernel ? Response Function, Fluctuation ? Dissipation, Kramers-Kronig Relations
The Dielectric Response Function and Sum Rules: Sum Rule of Thomas-Reiche-Kuhn (TRK), Random Phase Approximation, Optical Sum Rules
Appendix A: Principles of Scattering Theory
Appendix B: Form Factors
Appendix C: Reminder on Statistical Mechanics
Appendix D: The Magnetic Matrix-Elements
Appendix E: The Principle of a mu-SR-Experiment
Appendix F: Reflection Symmetry and Time-Reversal Invariance
Appendix G: Collective Excitations