C. Julian Chen
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780199211500
- eISBN:
- 9780191705991
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199211500.001.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
The scanning tunneling microscope (STM) and the atomic force microscope (AFM), both capable of visualizing and manipulating individual atoms, are the cornerstones of nanoscience and nanotechnology ...
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The scanning tunneling microscope (STM) and the atomic force microscope (AFM), both capable of visualizing and manipulating individual atoms, are the cornerstones of nanoscience and nanotechnology today. The inventors of STM, Gerd Binnig and Heinrich Rohrer, were awarded with the Nobel Prize of physics in 1986. Both microscopes are based on mechanically scanning an atomically sharp tip over a sample surface, with quantum-mechanical tunneling or atomic forces between the tip and the atoms on the sample as the measurable quantities. This book presents the principles of STM and AFM, and the experimental details. Part I presents the principles from a unified point of view: the Bardeen theory of tunneling phenomenon, and the Herring-Landau theory of covalent-bond force. The similarity between those two theories, both rooted from the Heisenberg-Pauling concept of quantum-mechanical resonance, points to the equivalence of tunneling and covalent-bond force. The Tersoff-Hamann model of STM is presented, including the original derivation. The mechanisms of atomic-scale imaging of both STM and AFM are discussed. Part II presents the instrumentation and experimental techniques of STM and AFM, including piezoelectric scanners, vibration isolation, electronics and control, mechanical design, tip treatment and characterization, scanning tunneling spectroscopy, and atomic force detection techniques. Part II ends with illustrative applications of STM and AFM in various fields of research and technology.Less
The scanning tunneling microscope (STM) and the atomic force microscope (AFM), both capable of visualizing and manipulating individual atoms, are the cornerstones of nanoscience and nanotechnology today. The inventors of STM, Gerd Binnig and Heinrich Rohrer, were awarded with the Nobel Prize of physics in 1986. Both microscopes are based on mechanically scanning an atomically sharp tip over a sample surface, with quantum-mechanical tunneling or atomic forces between the tip and the atoms on the sample as the measurable quantities. This book presents the principles of STM and AFM, and the experimental details. Part I presents the principles from a unified point of view: the Bardeen theory of tunneling phenomenon, and the Herring-Landau theory of covalent-bond force. The similarity between those two theories, both rooted from the Heisenberg-Pauling concept of quantum-mechanical resonance, points to the equivalence of tunneling and covalent-bond force. The Tersoff-Hamann model of STM is presented, including the original derivation. The mechanisms of atomic-scale imaging of both STM and AFM are discussed. Part II presents the instrumentation and experimental techniques of STM and AFM, including piezoelectric scanners, vibration isolation, electronics and control, mechanical design, tip treatment and characterization, scanning tunneling spectroscopy, and atomic force detection techniques. Part II ends with illustrative applications of STM and AFM in various fields of research and technology.
Sergey Ganichev and Willi Prettl
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198528302
- eISBN:
- 9780191713637
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198528302.001.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
This book presents high-power terahertz applications to semiconductors and semiconductor structures. It aims to bridge the gap between optics and microwave physics. It focuses on a core topic of ...
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This book presents high-power terahertz applications to semiconductors and semiconductor structures. It aims to bridge the gap between optics and microwave physics. It focuses on a core topic of semiconductor physics, providing a full description of the state of art of the field. The book introduces new physical phenomena which occur in the terahertz frequency range at the transition from semi-classical physics with a classical field amplitude to the fully quantized limit with photons. It covers tunneling in high-frequency fields, nonlinear absorption of radiation and radiation heating, nonlinear optics in the classical sense, Bloch-oscillations and ponderomotive forces of the terahertz radiation on free carriers, photon drag and photogalvanic effects, and terahertz spin dependent phenomena being of importance in the field of spintronics. Background information for future work and references of current literature are given. The book also discusses various experimental aspects like the generation of high-power coherent terahertz radiation, properties of materials with respect to their application in optical components, and detection schemes of short intense terahertz pulses.Less
This book presents high-power terahertz applications to semiconductors and semiconductor structures. It aims to bridge the gap between optics and microwave physics. It focuses on a core topic of semiconductor physics, providing a full description of the state of art of the field. The book introduces new physical phenomena which occur in the terahertz frequency range at the transition from semi-classical physics with a classical field amplitude to the fully quantized limit with photons. It covers tunneling in high-frequency fields, nonlinear absorption of radiation and radiation heating, nonlinear optics in the classical sense, Bloch-oscillations and ponderomotive forces of the terahertz radiation on free carriers, photon drag and photogalvanic effects, and terahertz spin dependent phenomena being of importance in the field of spintronics. Background information for future work and references of current literature are given. The book also discusses various experimental aspects like the generation of high-power coherent terahertz radiation, properties of materials with respect to their application in optical components, and detection schemes of short intense terahertz pulses.
Elias Burstein
- Published in print:
- 2007
- Published Online:
- May 2008
- ISBN:
- 9780199238873
- eISBN:
- 9780191716652
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199238873.003.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter includes recollections by Elias Burstein about his meetings with L. V. Keldysh in 1960s. It describes research links between US and USSR condensed matter physicists over four decades ...
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This chapter includes recollections by Elias Burstein about his meetings with L. V. Keldysh in 1960s. It describes research links between US and USSR condensed matter physicists over four decades ago, and the difficulty of organizing joint research meetings at that time.Less
This chapter includes recollections by Elias Burstein about his meetings with L. V. Keldysh in 1960s. It describes research links between US and USSR condensed matter physicists over four decades ago, and the difficulty of organizing joint research meetings at that time.
Lawrence Challis (ed.)
- Published in print:
- 2003
- Published Online:
- January 2010
- ISBN:
- 9780198507321
- eISBN:
- 9780191709319
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198507321.001.0001
- Subject:
- Physics, Atomic, Laser, and Optical Physics
The study of electrons and holes confined to two, one, and even zero dimensions has uncovered a rich variety of new physics and applications. This book describes the interaction between these ...
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The study of electrons and holes confined to two, one, and even zero dimensions has uncovered a rich variety of new physics and applications. This book describes the interaction between these confined carriers and the optic and acoustic phonons within and around the confined regions. Phonons provide the principal channel of energy transfer between the carriers and their surroundings and also the main restriction to their room temperature mobility. However, they also have many other roles; they contribute, for example, an essential feature to the operation of the quantum cascade laser. Since their momenta at relevant energies are well matched to those of electrons, they can also be used to probe electronic properties such as the confinement width of two-dimensional (2-D) electron gases and the dispersion curve of quasiparticles in the fractional quantum Hall effect. The book describes both the physics of the electron-phonon interaction in the different confined systems and the experimental and theoretical techniques that have been used in its investigation. The experimental methods include optical and transport techniques as well as techniques in which phonons are used as the experimental probe. This book provides an up-to-date review of the physics and its significance in device performance.Less
The study of electrons and holes confined to two, one, and even zero dimensions has uncovered a rich variety of new physics and applications. This book describes the interaction between these confined carriers and the optic and acoustic phonons within and around the confined regions. Phonons provide the principal channel of energy transfer between the carriers and their surroundings and also the main restriction to their room temperature mobility. However, they also have many other roles; they contribute, for example, an essential feature to the operation of the quantum cascade laser. Since their momenta at relevant energies are well matched to those of electrons, they can also be used to probe electronic properties such as the confinement width of two-dimensional (2-D) electron gases and the dispersion curve of quasiparticles in the fractional quantum Hall effect. The book describes both the physics of the electron-phonon interaction in the different confined systems and the experimental and theoretical techniques that have been used in its investigation. The experimental methods include optical and transport techniques as well as techniques in which phonons are used as the experimental probe. This book provides an up-to-date review of the physics and its significance in device performance.
Terry Gourvish
- Published in print:
- 2002
- Published Online:
- September 2007
- ISBN:
- 9780199250059
- eISBN:
- 9780191719516
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199250059.001.0001
- Subject:
- Business and Management, Business History
Britain's privatized railways continue to provoke debate about the organization, financing, and development of the railway system. This important book provides an authoritative account of the ...
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Britain's privatized railways continue to provoke debate about the organization, financing, and development of the railway system. This important book provides an authoritative account of the progress made by British Rail prior to privatization, and a unique insight into its difficult role in the government's privatization planning from 1989. Based on free access to the British Railway Board's archives, the book provides an analysis of the main themes: a process of continuous organizational change; the existence of a persistent government audit; perennial investment restraints; the directive to reduce operating costs and improve productivity; a concern with financial performance, technological change, service quality, and the management of industrial relations; and the Board's ambiguous position as the Conservative government pressed home its privatization programme. The introduction of sector management from 1982 and the ‘Organizing for Quality’ initiative of the early 1990s, the Serpell Report on railway finances of 1983, the sale of the subsidiary businesses, the large-scale investment in the Channel Tunnel, and the obsession with safety which followed the Clapham accident of 1988, are all examined. In the conclusion, the book reviews the successes and failures of the public sector, rehearses the arguments for and against integration in the railway industry, and contrasts what many have termed ‘the golden age’ of the mid-late 1980s, when the British Rail-government relationship was arguably at its most effective, with what has happened since 1994.Less
Britain's privatized railways continue to provoke debate about the organization, financing, and development of the railway system. This important book provides an authoritative account of the progress made by British Rail prior to privatization, and a unique insight into its difficult role in the government's privatization planning from 1989. Based on free access to the British Railway Board's archives, the book provides an analysis of the main themes: a process of continuous organizational change; the existence of a persistent government audit; perennial investment restraints; the directive to reduce operating costs and improve productivity; a concern with financial performance, technological change, service quality, and the management of industrial relations; and the Board's ambiguous position as the Conservative government pressed home its privatization programme. The introduction of sector management from 1982 and the ‘Organizing for Quality’ initiative of the early 1990s, the Serpell Report on railway finances of 1983, the sale of the subsidiary businesses, the large-scale investment in the Channel Tunnel, and the obsession with safety which followed the Clapham accident of 1988, are all examined. In the conclusion, the book reviews the successes and failures of the public sector, rehearses the arguments for and against integration in the railway industry, and contrasts what many have termed ‘the golden age’ of the mid-late 1980s, when the British Rail-government relationship was arguably at its most effective, with what has happened since 1994.
C. Julian Chen
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780199211500
- eISBN:
- 9780191705991
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199211500.003.0002
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter presents basic experimental methods and the basic theory of tunneling. The classical metal-insulator-metal tunneling junction experiment of Giaever, designed to verify the ...
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This chapter presents basic experimental methods and the basic theory of tunneling. The classical metal-insulator-metal tunneling junction experiment of Giaever, designed to verify the Bardeen-Cooper-Schrieffer theory of superconductivity, is the motivation for Bardeen to invent his perturbation theory of tunneling. That Bardeen theory then became the starting point of the most useful models of STM. Section 2.2 presents the Bardeen tunneling theory from time-dependent perturbation theory of quantum mechanics, starting from a one-dimensional case, then proceeds to three-dimensional version with wave-function corrections. The Bardeen theory in second-quantization format, the transfer-Hamiltonian formalism, is also presented. As extensions of the original Bardeen theory, the theories and experiments of inelastic tunneling and spin-polarized tunneling are discussed in depth.Less
This chapter presents basic experimental methods and the basic theory of tunneling. The classical metal-insulator-metal tunneling junction experiment of Giaever, designed to verify the Bardeen-Cooper-Schrieffer theory of superconductivity, is the motivation for Bardeen to invent his perturbation theory of tunneling. That Bardeen theory then became the starting point of the most useful models of STM. Section 2.2 presents the Bardeen tunneling theory from time-dependent perturbation theory of quantum mechanics, starting from a one-dimensional case, then proceeds to three-dimensional version with wave-function corrections. The Bardeen theory in second-quantization format, the transfer-Hamiltonian formalism, is also presented. As extensions of the original Bardeen theory, the theories and experiments of inelastic tunneling and spin-polarized tunneling are discussed in depth.
Terry Gourvish
- Published in print:
- 2002
- Published Online:
- September 2007
- ISBN:
- 9780199250059
- eISBN:
- 9780191719516
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199250059.003.0009
- Subject:
- Business and Management, Business History
This chapter focuses on railway investments. Topics discussed include investment promotion, reduced investment spending in 1990, the need for project management and procurement, and investments on ...
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This chapter focuses on railway investments. Topics discussed include investment promotion, reduced investment spending in 1990, the need for project management and procurement, and investments on Channel Tunnel services and the High-Speed Rail Link.Less
This chapter focuses on railway investments. Topics discussed include investment promotion, reduced investment spending in 1990, the need for project management and procurement, and investments on Channel Tunnel services and the High-Speed Rail Link.
L.J. Challis
- Published in print:
- 2003
- Published Online:
- January 2010
- ISBN:
- 9780198507321
- eISBN:
- 9780191709319
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198507321.003.0001
- Subject:
- Physics, Atomic, Laser, and Optical Physics
While the physics of low-dimensional structures mainly involves their electronic properties, an understanding of the interaction between the electrons and holes and the phonons present within and ...
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While the physics of low-dimensional structures mainly involves their electronic properties, an understanding of the interaction between the electrons and holes and the phonons present within and around the confined layers is frequently needed if this physics is to be understood in detail. This introductory chapter gives examples of this and outlines the experimental methods that have been used to study the electron-phonon interactions. These include both optical and transport techniques and also techniques that involve the use of phonons as probes: phonon techniques. Phonons interact much more strongly with electrons than photons of the same frequency since their momenta are usually much closer to those of the confined electrons, and phonon techniques have been used to obtain information ranging from the confinement widths to the dispersion curve of quasiparticles in the fractional quantum Hall state.Less
While the physics of low-dimensional structures mainly involves their electronic properties, an understanding of the interaction between the electrons and holes and the phonons present within and around the confined layers is frequently needed if this physics is to be understood in detail. This introductory chapter gives examples of this and outlines the experimental methods that have been used to study the electron-phonon interactions. These include both optical and transport techniques and also techniques that involve the use of phonons as probes: phonon techniques. Phonons interact much more strongly with electrons than photons of the same frequency since their momenta are usually much closer to those of the confined electrons, and phonon techniques have been used to obtain information ranging from the confinement widths to the dispersion curve of quasiparticles in the fractional quantum Hall state.
J. Eduardo P. W. Bicudo, William A. Buttemer, Mark A. Chappell, James T. Pearson, and Claus Bech
- Published in print:
- 2010
- Published Online:
- May 2010
- ISBN:
- 9780199228447
- eISBN:
- 9780191711305
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199228447.003.0008
- Subject:
- Biology, Ornithology
The emergence of new techniques, methods, and analytical approaches is hard to predict. Research on avian biology has greatly benefitted from technical advances (for example tracking technology), and ...
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The emergence of new techniques, methods, and analytical approaches is hard to predict. Research on avian biology has greatly benefitted from technical advances (for example tracking technology), and it should continue to do so in the coming decades. From that perspective, this chapter briefly discusses several new areas of research that it is believed will profoundly influence our understanding of avian biology in general and evolutionary physiology in particular. These range from molecular and genomic methods, to new technical approaches addressing longstanding physiological questions.Less
The emergence of new techniques, methods, and analytical approaches is hard to predict. Research on avian biology has greatly benefitted from technical advances (for example tracking technology), and it should continue to do so in the coming decades. From that perspective, this chapter briefly discusses several new areas of research that it is believed will profoundly influence our understanding of avian biology in general and evolutionary physiology in particular. These range from molecular and genomic methods, to new technical approaches addressing longstanding physiological questions.
S. D. Ganichev and W. Prettl
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198528302
- eISBN:
- 9780191713637
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198528302.003.0003
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter deals with tunneling phenomena in high-frequency alternating fields comprising solely terahertz field-induced tunneling as well as terahertz radiation-mediated tunneling in static ...
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This chapter deals with tunneling phenomena in high-frequency alternating fields comprising solely terahertz field-induced tunneling as well as terahertz radiation-mediated tunneling in static electric fields. The enhancement of tunneling probability with rising radiation frequency is treated in detail from an experimental and theoretical point of view. Tunneling in THz-field provides a method for characterizing semiconductors. In particular, the determination of tunneling times is sketched. The effect of THz-radiation on tunneling in dc-fields is also described, including photon assisted tunneling and ponderomotive action of radiation on electrons.Less
This chapter deals with tunneling phenomena in high-frequency alternating fields comprising solely terahertz field-induced tunneling as well as terahertz radiation-mediated tunneling in static electric fields. The enhancement of tunneling probability with rising radiation frequency is treated in detail from an experimental and theoretical point of view. Tunneling in THz-field provides a method for characterizing semiconductors. In particular, the determination of tunneling times is sketched. The effect of THz-radiation on tunneling in dc-fields is also described, including photon assisted tunneling and ponderomotive action of radiation on electrons.
Anatoly Larkin and Andrei Varlamov
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198528159
- eISBN:
- 9780191713521
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198528159.003.0009
- Subject:
- Physics, Condensed Matter Physics / Materials
The chapter starts with a discussion of the density of states renormalization in the normal state of a superconductor caused by fluctuation pairing which occurs close to the transition temperature. ...
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The chapter starts with a discussion of the density of states renormalization in the normal state of a superconductor caused by fluctuation pairing which occurs close to the transition temperature. The manifestation of this fluctuation renormalization in the tunnel current of the N(S)-I-S (S) junction is then discussed. In order to derive the general formula for the current in an arbitrary tunnel structure, the effective boundary Hamiltonian is introduced, which allows for the study of fluctuation phenomena in N(S)-I-S junction. The fluctuation tunneling anomaly in a superconductor above the paramagnetic limit is discussed. The effect of quantum fluctuations on magnetoresistance of a granular superconducting metal is considered.Less
The chapter starts with a discussion of the density of states renormalization in the normal state of a superconductor caused by fluctuation pairing which occurs close to the transition temperature. The manifestation of this fluctuation renormalization in the tunnel current of the N(S)-I-S (S) junction is then discussed. In order to derive the general formula for the current in an arbitrary tunnel structure, the effective boundary Hamiltonian is introduced, which allows for the study of fluctuation phenomena in N(S)-I-S junction. The fluctuation tunneling anomaly in a superconductor above the paramagnetic limit is discussed. The effect of quantum fluctuations on magnetoresistance of a granular superconducting metal is considered.
Dante Gatteschi, Roberta Sessoli, and Jacques Villain
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780198567530
- eISBN:
- 9780191718298
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567530.003.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter introduces the field of molecular magnetism with a brief overview of the main properties. It takes a historical point of view. Concepts such as magnetic anisotropy, superparamagnetism, ...
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This chapter introduces the field of molecular magnetism with a brief overview of the main properties. It takes a historical point of view. Concepts such as magnetic anisotropy, superparamagnetism, and magnetic relaxation, which are the keys to understanding how the bulk behaviour arises from nanomagnetism, are discussed first. The concept of single molecule magnet is introduced next, with the coexistence of classical and quantum effects, such as magnetization tunnelling and oscillation of the tunnel splitting. The last part of the chapter is devoted to describing the structure of the book, indicating the content of the various chapters.Less
This chapter introduces the field of molecular magnetism with a brief overview of the main properties. It takes a historical point of view. Concepts such as magnetic anisotropy, superparamagnetism, and magnetic relaxation, which are the keys to understanding how the bulk behaviour arises from nanomagnetism, are discussed first. The concept of single molecule magnet is introduced next, with the coexistence of classical and quantum effects, such as magnetization tunnelling and oscillation of the tunnel splitting. The last part of the chapter is devoted to describing the structure of the book, indicating the content of the various chapters.
Dante Gatteschi, Roberta Sessoli, and Jacques Villain
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780198567530
- eISBN:
- 9780191718298
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567530.003.0006
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter introduces the magnetic tunnelling of an isolated spin. The tunnel effect of the magnetization is compared to that of a particle. The symmetry and the selection rules for tunnelling are ...
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This chapter introduces the magnetic tunnelling of an isolated spin. The tunnel effect of the magnetization is compared to that of a particle. The symmetry and the selection rules for tunnelling are worked out, and the concept of tunnelling width and tunnel splitting are discussed. The effect of an applied magnetic field on the tunnel splitting is described, with particular emphasis on a field along the hard axis. The discussion is then specialized to large spins, taking into account the role of a magnetic anisotropy of transverse type. The concept of diabolic points where accidental degeneration of levels occurs, and their influence on the tunnel splitting is discussed, with examples taken by experimental investigations on the cluster Fe8.Less
This chapter introduces the magnetic tunnelling of an isolated spin. The tunnel effect of the magnetization is compared to that of a particle. The symmetry and the selection rules for tunnelling are worked out, and the concept of tunnelling width and tunnel splitting are discussed. The effect of an applied magnetic field on the tunnel splitting is described, with particular emphasis on a field along the hard axis. The discussion is then specialized to large spins, taking into account the role of a magnetic anisotropy of transverse type. The concept of diabolic points where accidental degeneration of levels occurs, and their influence on the tunnel splitting is discussed, with examples taken by experimental investigations on the cluster Fe8.
C. Julian Chen
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780199211500
- eISBN:
- 9780191705991
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199211500.003.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter presents the basic designs and working principles of STM and AFM, as well as an elementary theory of tunneling and the imaging mechanism of atomic resolution. Three elementary theories ...
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This chapter presents the basic designs and working principles of STM and AFM, as well as an elementary theory of tunneling and the imaging mechanism of atomic resolution. Three elementary theories of tunneling are presented: the one-dimensional Schrödinger's equation in vacuum, the semi-classical approximation, and the Landauer formalism. The relation between the decay constant and the work function, and a general expression of tunneling conductance versus tip-sample distance are derived. A brief summary of experimental facts on the mechanism of atomic resolution STM and AFM is presented, which leads to a picture of interplay between the atomic states of the tip and the sample, as well as the role of partial covalent bonds formed between those electronic states. As an introduction to the concept of equivalence of tunneling and atomic forces, atom and molecule manipulation is briefly presented.Less
This chapter presents the basic designs and working principles of STM and AFM, as well as an elementary theory of tunneling and the imaging mechanism of atomic resolution. Three elementary theories of tunneling are presented: the one-dimensional Schrödinger's equation in vacuum, the semi-classical approximation, and the Landauer formalism. The relation between the decay constant and the work function, and a general expression of tunneling conductance versus tip-sample distance are derived. A brief summary of experimental facts on the mechanism of atomic resolution STM and AFM is presented, which leads to a picture of interplay between the atomic states of the tip and the sample, as well as the role of partial covalent bonds formed between those electronic states. As an introduction to the concept of equivalence of tunneling and atomic forces, atom and molecule manipulation is briefly presented.
C. Julian Chen
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780199211500
- eISBN:
- 9780191705991
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199211500.003.0005
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter presents a unified theory of tunneling phenomenon and covalent bond force, as a result of the similarity between the Bardeen theory of tunneling and the Herring-Landau theory of the ...
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This chapter presents a unified theory of tunneling phenomenon and covalent bond force, as a result of the similarity between the Bardeen theory of tunneling and the Herring-Landau theory of the covalent bond. Three general theoretical treatments are presented, which show that tunneling conductance is proportional to the square of the covalent bond interaction energy, or equivalently, the square of covalent bond force. The constant of proportionality is related to the electronic properties of the materials. For the case of a metal tip and a metal sample, an explicit equation contains only measurable physical quantities is derived. Several experimental verifications are presented. The equivalence of covalent bond energy and tunneling conductance provides a theoretical explanation of the threshold resistance observed in atom-manipulation experiments, and points to a method of predicting the threshold resistance for atom manipulation.Less
This chapter presents a unified theory of tunneling phenomenon and covalent bond force, as a result of the similarity between the Bardeen theory of tunneling and the Herring-Landau theory of the covalent bond. Three general theoretical treatments are presented, which show that tunneling conductance is proportional to the square of the covalent bond interaction energy, or equivalently, the square of covalent bond force. The constant of proportionality is related to the electronic properties of the materials. For the case of a metal tip and a metal sample, an explicit equation contains only measurable physical quantities is derived. Several experimental verifications are presented. The equivalence of covalent bond energy and tunneling conductance provides a theoretical explanation of the threshold resistance observed in atom-manipulation experiments, and points to a method of predicting the threshold resistance for atom manipulation.
Xin Jiang and Stuart Parkin
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780198568216
- eISBN:
- 9780191718212
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198568216.003.0006
- Subject:
- Physics, Condensed Matter Physics / Materials
Highly spin-polarized electron currents can be engineered in magnetic nanostructures by utilizing spin dependent tunneling and spin dependent scattering effects. In magnetic tunnel junctions with ...
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Highly spin-polarized electron currents can be engineered in magnetic nanostructures by utilizing spin dependent tunneling and spin dependent scattering effects. In magnetic tunnel junctions with crystalline MgO barriers, a giant asymmetry in tunneling probability for the majority and minority electrons gives rise to currents which are more than 85% spin polarized at low temperatures and corresponding tunneling magnetoresistance values of more than 200% at room temperature. In a three terminal magnetic tunnel transistor (MTT), the electron current is further spin-filtered in a magnetic base layer so that the collector current can become nearly completely spin-polarized. The MTT allows for the exploration of spin dependent scattering of hot electrons and can be used as a spin injector into semiconductors, but the high energy of the injected electrons leads to modest values of spin polarization. More highly spin polarized currents can be injected into semiconductors using tunnel spin injectors such as CoFe/MgO.Less
Highly spin-polarized electron currents can be engineered in magnetic nanostructures by utilizing spin dependent tunneling and spin dependent scattering effects. In magnetic tunnel junctions with crystalline MgO barriers, a giant asymmetry in tunneling probability for the majority and minority electrons gives rise to currents which are more than 85% spin polarized at low temperatures and corresponding tunneling magnetoresistance values of more than 200% at room temperature. In a three terminal magnetic tunnel transistor (MTT), the electron current is further spin-filtered in a magnetic base layer so that the collector current can become nearly completely spin-polarized. The MTT allows for the exploration of spin dependent scattering of hot electrons and can be used as a spin injector into semiconductors, but the high energy of the injected electrons leads to modest values of spin polarization. More highly spin polarized currents can be injected into semiconductors using tunnel spin injectors such as CoFe/MgO.
John J. Videler
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780199299928
- eISBN:
- 9780191714924
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199299928.003.0008
- Subject:
- Biology, Ornithology
The metabolic costs of flapping flight were measured in 37 species using a variety of techniques. Data included free flight and wind tunnel studies. The loss of body mass after long distance flights ...
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The metabolic costs of flapping flight were measured in 37 species using a variety of techniques. Data included free flight and wind tunnel studies. The loss of body mass after long distance flights and food balance experiments under controlled conditions provided reliable figures. Flight costs were also derived from measurements of the exchange of respiratory gasses, and from changes in the concentrations of stable heavy isotopes of oxygen and hydrogen injected in the blood. Heart rate telemetry is another indirect way to detect oxygen consumption. To determine flight costs, knowledge of the substance burnt is required — a condition which is difficult to meet. The decay of the concentration of a stable carbon isotope also yields reliable figures. Eleven reliable metabolic costs studies using respirometry of hovering flight include ten hummingbirds and one sunbird.Less
The metabolic costs of flapping flight were measured in 37 species using a variety of techniques. Data included free flight and wind tunnel studies. The loss of body mass after long distance flights and food balance experiments under controlled conditions provided reliable figures. Flight costs were also derived from measurements of the exchange of respiratory gasses, and from changes in the concentrations of stable heavy isotopes of oxygen and hydrogen injected in the blood. Heart rate telemetry is another indirect way to detect oxygen consumption. To determine flight costs, knowledge of the substance burnt is required — a condition which is difficult to meet. The decay of the concentration of a stable carbon isotope also yields reliable figures. Eleven reliable metabolic costs studies using respirometry of hovering flight include ten hummingbirds and one sunbird.
Albert O. Hirschman
- Published in print:
- 2013
- Published Online:
- October 2017
- ISBN:
- 9780691159904
- eISBN:
- 9781400848409
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691159904.003.0004
- Subject:
- Sociology, Social Theory
This chapter discusses the complicated relationship between perception and reality in development. It explores the role of emotions and subjective forces—especially envy—in arguing that just as ...
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This chapter discusses the complicated relationship between perception and reality in development. It explores the role of emotions and subjective forces—especially envy—in arguing that just as social scientists and policy makers should not confuse circumstantial setbacks with failure in development, rising intolerance for inequality need not be seen as a sign of a crisis of capitalism, or of having to choose between growth or equality. Psychological effects, like the “tunnel effect,” are highly contingent, and one has to understand them carefully before jumping to big conclusions. After all, a strong tunnel effect, by making social injustice more visible, can have positive repercussions.Less
This chapter discusses the complicated relationship between perception and reality in development. It explores the role of emotions and subjective forces—especially envy—in arguing that just as social scientists and policy makers should not confuse circumstantial setbacks with failure in development, rising intolerance for inequality need not be seen as a sign of a crisis of capitalism, or of having to choose between growth or equality. Psychological effects, like the “tunnel effect,” are highly contingent, and one has to understand them carefully before jumping to big conclusions. After all, a strong tunnel effect, by making social injustice more visible, can have positive repercussions.
NEVILLE WYLIE
- Published in print:
- 2003
- Published Online:
- January 2010
- ISBN:
- 9780198206903
- eISBN:
- 9780191717338
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198206903.003.0006
- Subject:
- History, British and Irish Modern History, European Modern History
Switzerland's success in deterring a German attack after 1940 writs large in popular depictions of Switzerland's wartime history, and played a decisive part in helping to elevate neutrality as the ...
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Switzerland's success in deterring a German attack after 1940 writs large in popular depictions of Switzerland's wartime history, and played a decisive part in helping to elevate neutrality as the country's core foreign policy maxim during the cold war. This chapter shows that although British military observers were impressed by Swiss defences, Switzerland rarely featured in British strategic deliberations, nor was it deemed sufficiently important to justify releasing military and strategic resources for Swiss use through the blockade. Moreover, the defence of the Alpine railway tunnels, upon which Swiss deterrent strategy relied, ultimately worked to Britain's disadvantage as it guaranteed the Axis unfettered access to Swiss transit facilities. The chapter examines Britain's lacklustre diplomatic and military efforts to reduce Axis transit traffic across Switzerland.Less
Switzerland's success in deterring a German attack after 1940 writs large in popular depictions of Switzerland's wartime history, and played a decisive part in helping to elevate neutrality as the country's core foreign policy maxim during the cold war. This chapter shows that although British military observers were impressed by Swiss defences, Switzerland rarely featured in British strategic deliberations, nor was it deemed sufficiently important to justify releasing military and strategic resources for Swiss use through the blockade. Moreover, the defence of the Alpine railway tunnels, upon which Swiss deterrent strategy relied, ultimately worked to Britain's disadvantage as it guaranteed the Axis unfettered access to Swiss transit facilities. The chapter examines Britain's lacklustre diplomatic and military efforts to reduce Axis transit traffic across Switzerland.
Gregory L. Simon
- Published in print:
- 2016
- Published Online:
- May 2017
- ISBN:
- 9780520292802
- eISBN:
- 9780520966161
- Item type:
- book
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520292802.001.0001
- Subject:
- Earth Sciences and Geography, Environmental Geography
This book investigates the ongoing politics, folly, and avarice shaping the production of increasingly widespread yet dangerous suburban and exurban landscapes. The 1991 Oakland Hills Tunnel Fire is ...
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This book investigates the ongoing politics, folly, and avarice shaping the production of increasingly widespread yet dangerous suburban and exurban landscapes. The 1991 Oakland Hills Tunnel Fire is used as a starting point to better understand these complex social-environmental processes. The Tunnel Fire is the most destructive fire—in terms of structures lost—in California history. More than 3,000 residential structures burned and 25 lives were lost. Although this fire occurred in Oakland and Berkeley, others like it sear through landscapes in California and the American West that have experienced urban growth and development within areas historically prone to fire. The book blends environmental history, political ecology, and science studies to closely examine the Tunnel Fire within a broader historical and spatial context of regional economic development and natural-resource management, such as the widespread planting of eucalyptus trees as an exotic lure for homeowners and the creation of hillside neighborhoods for tax revenue—decisions that produced communities with increased vulnerability to fire. The book demonstrates how in Oakland a drive for affluence led to a state of vulnerability for rich and poor alike that has only been exacerbated by the rebuilding of neighborhoods after the fire. Despite these troubling trends, the text illustrates how many popular and scientific debates on fire limit the scope and efficacy of policy responses. These risky yet profitable developments (what the book refers to as the Incendiary), as well as proposed strategies for challenging them, are discussed in the context of urbanizing areas around the American West and hold global applicability within hazard-prone areas.Less
This book investigates the ongoing politics, folly, and avarice shaping the production of increasingly widespread yet dangerous suburban and exurban landscapes. The 1991 Oakland Hills Tunnel Fire is used as a starting point to better understand these complex social-environmental processes. The Tunnel Fire is the most destructive fire—in terms of structures lost—in California history. More than 3,000 residential structures burned and 25 lives were lost. Although this fire occurred in Oakland and Berkeley, others like it sear through landscapes in California and the American West that have experienced urban growth and development within areas historically prone to fire. The book blends environmental history, political ecology, and science studies to closely examine the Tunnel Fire within a broader historical and spatial context of regional economic development and natural-resource management, such as the widespread planting of eucalyptus trees as an exotic lure for homeowners and the creation of hillside neighborhoods for tax revenue—decisions that produced communities with increased vulnerability to fire. The book demonstrates how in Oakland a drive for affluence led to a state of vulnerability for rich and poor alike that has only been exacerbated by the rebuilding of neighborhoods after the fire. Despite these troubling trends, the text illustrates how many popular and scientific debates on fire limit the scope and efficacy of policy responses. These risky yet profitable developments (what the book refers to as the Incendiary), as well as proposed strategies for challenging them, are discussed in the context of urbanizing areas around the American West and hold global applicability within hazard-prone areas.
