Preface ................................................... XVII
List of Contributors ....................................... XIX
Color Plate .............................................. XXVII
(after page 379)
Part One Quasiparticle Dynamics ................................ 1
1 Nonlinear Terahertz Studies of Ultrafast Quasiparticle
Dynamics in Semiconductors ................................... 3
Michael Woerner and Thomas Elsaesser
1.1 Linear Optical Properties of Quasiparticles: The
Polarization Cloud around a Charge Carrier .............. 4
1.1.1 Theoretical Models Describing Static and
Dynamic Properties of Polarons ................... 5
1.1.2 Experimental Signatures of linear and
Quasistationary Polaron Properties ............... 8
1.1.2.1 The Fröhlich Polaron at Rest ............ 8
1.1.2.2 Frequency-Dependent Mobility of the
Fröhlich Polaron ........................ 9
1.1.2.3 Quasistationary High-Field Transport
of Polarons ............................ 11
1.2 Femtosecond Nonlinear Terahertz and Mid-Infrared
Spectroscopy
1.2.1 Generation of High-Field Terahertz Transients ... 13
1.2.2 Electric Field-Resolved THz Pump-Mid-Infrared
Probe Experiments ............................... 15
1.2.3 Nonlinear Terahertz Transmission Experiments .... 17
1.3 Ultrafast Quantum Kinetics of Polarons in Bulk GaAs .... 20
1.3.1 Experimental Results ............................ 20
1.3.2 Discussion ...................................... 22
1.4 Coherent High-Field Transport in GaAs on Femtosecond
Timescales ............................................. 23
1.4.1 Experimental Results ............................ 24
1.4.2 Discussion ...................................... 26
1.5 Conclusions and Outlook ................................ 28
References .................................................. 28
2 Higher Order Photoemission from Metal Surfaces .............. 33
Aimo Winkelmann, Cheng-Tien Chiang, Francesco Bisio,
Wen-Chin Lin, Jürgen Kirschner, and Hrvoje Petek
2.1 Introduction ........................................... 33
2.2 Observation of Higher Order Photoemission at Cu
Surfaces ............................................... 34
2.2.1 Resonant 3PPE in the Cu(001) Electronic Band
Structure ....................................... 36
2.3 Electronic Structure Mapping Using Coherent
Multiphoton Resonances ................................. 39
2.4 Dynamical Trapping of Electrons in Quasibound States ... 44
2.5 Above-Threshold Photoemission .......................... 46
2.6 Spin-Polarized Multiphoton Photoemission ............... 47
2.7 Summary and Outlook .................................... 48
References ............................................. 49
3 Electron Dynamics in Image Potential States at Metal
Surfaces .................................................... 53
Thomas Fauster
3.1 Scattering Processes ................................... 53
3.2 Energies and Dispersion of Image Potential States ...... 55
3.3 Inelastic Scattering ................................... 57
3.3.1 Lifetimes of Image Potential States ............. 57
3.3.2 Momentum Dependence of Lifetimes ................ 60
3.3.3 Inelastic Intraband Scattering .................. 61
3.3.4 Inelastic Interband Scattering .................. 62
3.4 Quasielastic Scattering ................................ 63
3.4.1 Elastic Interband Scattering .................... 63
3.4.2 Resonant Interband Scattering ................... 64
3.4.3 Elastic Intraband Scattering .................... 66
3.5 Electron-Phonon Scattering ............................. 67
3.6 Electron Defect Scattering ............................. 69
3.6.1 Scattering by Adatoms ........................... 69
3.6.2 Scattering by Steps ............................. 71
3.7 Summary and Outlook .................................... 72
References .................................................. 72
4 Relaxation Dynamics in Image Potential States at Solid
Interfaces .................................................. 75
James E. Johns, Eric Mьller, Matthew L. Strader, Sean
Carrett-Roe, and Charles B. Harris
4.1 Stochastic Interpretation of IPS Decay ................. 80
4.2 IPS Decay for Solvating Molecules ...................... 87
4.3 Conclusions ............................................ 94
References .................................................. 95
5 Dynamics of Electronic States at Metal/Insulator
Interfaces .................................................. 99
Jens Cüdde and Ulrich Höfer
5.1 Introduction ........................................... 99
5.2 Spectroscopy by One-Photon Photoemission .............. 101
5.3 Observation by Two-Photon Photoemission ............... 104
5.4 Lifetimes ............................................. 106
5.5 Momentum-Resolved Dynamics ............................ 108
5.6 Summary ............................................... 111
References ................................................. 111
6 Spin-Dependent Relaxation of Photoexcited Electrons at
Surfaces of 3d Ferromagnets ................................ 115
Martin Weineh, Anke В. Schmidt, Martin Pickel, and
Markus Donath
6.1 Introduction .......................................... 115
6.2 Spin-Resolved Two-Photon Photoemission on Image
Potential States ...................................... 116
6.2.1 Image Potential States at a Ferromagnetic
Surface ........................................ 116
6.2.2 Spin-Resolved Two-Photon Photoemission ......... 117
6.2.3 Key Aspects of the Experiment .................. 122
6.3 Spin-Dependent Dynamics ............................... 124
6.3.1 Spin-Dependent Population Decay of Bulk
Electrons ...................................... 124
6.3.2 Spin-Dependent Lifetimes of Image Potential
States ......................................... 127
6.3.3 Quasielastic Scattering: Spin-Dependent
Dephasing ...................................... 128
6.3.4 Inelastic Intraband Scattering: Magnon
Emission ....................................... 131
6.4 Image Potential States: A Sensor for Surface
Magnetization ......................................... 133
6.4.1 Projecting the Spin Polarization of Bulk and
Surface States ................................. 133
6.4.2 Access to Spin-Orbit Coupling via Dichroism .... 135
6.5 Summary ............................................... 139
References ................................................. 140
7 Electron-Phonon Interaction at Interfaces .................. 145
Philip Hofmann, Evgueni V. Chulkov, and Irina
Yu. Sklyadneva
7.1 Introduction .......................................... 145
7.2 Calculation of the Electron-Phonon Coupling
Strength .............................................. 147
7.3 Experimental Determination of the Electron-Phonon
Coupling Strength ..................................... 152
7.4 Some Examples ......................................... 157
7.4.1 The (111) Surface of the Noble Metals .......... 158
7.4.2 Be(0001) ....................................... 159
7.4.3 Mg(0001) and Al(001) ........................... 160
7.5 Conclusions ........................................... 161
References ................................................. 161
Part Two Collective Excitations .............................. 167
8 Low-Energy Collective Electronic Excitations at Metal
Surfaces ................................................... 169
Vyacheslav M. Silkin, Evgueni V. Chulkov, and Pedro
M. Echenique
8.1 Introduction .......................................... 169
8.2 Analytical and Numerical Calculations ................. 170
8.2.1 Some Analytical Results ........................ 170
8.2.2 Self-Consistent Dielectric Response ............ 172
8.3 Results of Numerical Calculations ..................... 175
8.3.1 Monolayers ..................................... 175
8.3.2 Metal Surfaces ................................. 177
8.3.2.1 1D Calculations ....................... 177
8.3.3 3D Calculations ................................ 180
8.3.4 Dynamical Charge Density Oscillations .......... 182
8.3.5 Acoustic Surface Plasmon Interaction with
Light .......................................... 184
8.4 Concluding Remarks .................................... 186
References ................................................. 186
9 Low-Dimensional Plasmons in Atom Sheets and Atom Chains .... 189
Tadaaki Nagao
9.1 Introduction .......................................... 189
9.2 Difference between the Surface Plasmons and the
Atomic Scale Plasmons ................................. 190
9.3 Measurement of Atomic Scale Low-Dimensional Metallic
Objects ............................................... 191
9.4 Plasmons Confined in Ag Nanolayers .................... 193
9.5 Plasmon in a Two-Dimensional Monoatomic Ag Layer ...... 197
9.6 Plasmons in Atomic Scale Quantum Wires ................ 202
9.6.1 Plasmons in Self-Assembled Au Atom Chains ...... 203
9.6.2 Plasmons in In-Induced Atom Chains ............. 207
9.7 Conclusions ........................................... 210
References ................................................. 210
10 Excitation and Time-Evolution of Coherent Optical
Phonons .................................................... 213
Muneaki Hase, Oleg V. Misochko, and Kunie Ishioka
10.1 Coherent Phonons in Group V Semimetals ............... 213
10.1.1 Generation and Relaxation of Different
Symmetry Phonons ............................... 214
10.1.2 Coherent Phonons in Extreme Nonequilibrium
Conditions ..................................... 216
10.1.3 Time-Resolved X-Ray Detection .................. 218
10.1.4 Optical Coherent Control ....................... 220
10.2 Ultrafast Electron-Phonon Coupling in Graphitic
Materials ............................................. 221
10.3 Quasiparticle Dynamics in Silicon ..................... 226
10.4 Coherent Optical Phonons in Metals .................... 227
10.5 Coherent Phonon-Polaritons in Ferroelectrics .......... 229
10.6 Current Developments in Other Materials ............... 231
10.7 Concluding Remarks .................................... 232
References ................................................. 233
11 Photoinduced Coherent Nuclear Motion at Surfaces: Alkali
Overlayers on Metals ....................................... 239
Yoshiyasu Matsumoto and Kazuya Watanabe
11.1 Introduction .......................................... 239
11.2 Impulsive Excitation .................................. 240
11.3 Alkali Metal Overlayers ............................... 242
11.3.1 Adsorbate Structures ........................... 242
11.3.2 Surface Phonon Bands ........................... 243
11.3.3 Electronic Structures .......................... 245
11.4 Time-Resolved SHG Spectroscopy ........................ 247
11.4.1 Enhancement of SHG Intensity by Alkali
Adsorption ..................................... 247
11.4.2 The Principle of TRSHG Spectroscopy ............ 249
11.5 Electronic and Nuclear Responses in TRSHG Signals ..... 250
11.5.1 Representative TRSHG Traces .................... 250
11.5.2 Electronic Response ............................ 251
11.5.3 Nuclear Response ............................... 252
11.5.4 Initial Phase .................................. 255
11.6 Excitation Mechanism .................................. 256
11.7 Summary and Outlook ................................... 260
References ................................................. 260
12 Coherent Excitations at Ferromagnetic Cd(0001) and
Tb(0001) Surfaces .......................................... 263
Alexey Melnikov and Uwe Bovensiepen
12.1 Introduction .......................................... 263
12.2 Relaxation of the Optically Excited State ............. 264
12.3 Coupled Lattice and Spin Excitations .................. 267
12.3.1 Transient Binding Energy Variations of the
Surface State .................................. 267
12.3.2 Nonlinear Optics as a Simultaneous Probe of
Lattice Vibrations and Magnetic Excitations .... 268
12.3.2.1 Magneto-Induced SHG: Experimental
Scheme and Data Analysis .............. 269
12.3.2.2 Magneto-Induced SHG: Coherent
Surface Dynamics ...................... 272
12.3.2.3 The Mechanism of Coherent Phonon
Excitation ............................ 274
12.3.2.4 Damping of the Coherent Phonons ....... 278
12.3.2.5 Future Developments ................... 279
12.4 Conclusion ............................................ 280
References ................................................. 281
Part Three Heterogeneous Electron Transfer .................... 283
13 Studies on Auger Neutralization of He+ Ions in Front of
Metal Surfaces ............................................. 285
Stephan Wethekam and Helmut Winkler
13.1 Introduction .......................................... 285
13.2 Concept of Method ..................................... 286
13.2.1 Trajectories and Time Regime ................... 288
13.3 Studies on Auger Neutralization of He+ Ions ........... 291
13.3.1 Studies on Auger Neutralization Making use of
Isotope Effect ................................. 298
13.3.2 Face Dependence of Auger Neutralization ........ 300
13.3.3 Effect of Magnetization of Target Surface on
Auger Neutralization ........................... 301
13.4 Summary and Conclusions ............................... 303
References ................................................. 303
14 Electron Transfer Investigated by X-Ray Spectroscopy ....... 305
Wilfried Wurth and Alexander Föhlisch
14.1 Core Hole Clock Spectroscopy .......................... 305
14.1.1 Basics ......................................... 306
14.1.2 Electron Stabilization ......................... 309
14.1.3 Attosecond Charge Transfer and the Effect of
Orbital Polarization ........................... 311
14.1.4 Clocks with Different Timing ................... 314
14.2 Time-Resolved Soft X-Ray Spectroscopy ................. 315
14.2.1 Laser-Assisted Photoemission ................... 318
14.2.2 Surface Carrier Dynamics ....................... 319
14.3 Summary ............................................... 320
References ................................................. 322
15 Exciton Formation and Decay at Surfaces and Interfaces ..... 325
Matthias Muntwiler and Xiaoyang Zhu
15.1 Introduction .......................................... 325
15.1.1 Exciton Flavors ................................ 326
15.1.2 Photophysics of Organic Semiconductors ......... 326
15.2 Exciton Models ........................................ 328
15.2.1 Dielectric Models .............................. 329
15.2.1.1 Mott-Wannier Exciton .................. 330
15.2.1.2 Charge Transfer Exciton at
Dielectric Interfaces ................. 330
15.2.2 Merrifield Model of Frenkel and Charge
Transfer Excitons .............................. 334
15.2.2.1 Frenkel Exciton ....................... 335
15.2.2.2 Charge Transfer Exciton ............... 337
15.2.2.3 Finite Size Effect .................... 338
15.3 Photoelectron Spectroscopy of Excitons ................ 338
15.3.1 Energy Levels .................................. 339
15.4 Frenkel Excitons in C60 ............................... 341
15.4.1 Structural Overview ............................ 341
15.4.2 Energy Levels .................................. 342
15.4.3 Exciton Dynamics ............................... 346
15.4.3.1 Coverage Dependence: Distance-
Dependent Quenching ................... 346
15.5 Charge Transfer Excitons at the Surface of
Pentacene ............................................. 349
15.5.1 System Overview ................................ 349
15.5.2 Energy Levels .................................. 350
15.5.3 Dynamics ....................................... 353
15.6 Conclusions ........................................... 354
References ................................................. 356
16 Electron Dynamics at Polar Molecule-Metal Interfaces:
Competition between Localization, Solvation, and
Transfer ................................................... 359
Julia Stähler, Uwe Bovensiepen, and Martin Wolf
16.1 Introduction .......................................... 359
16.2 Competing Channels of Electron Relaxation in
Amorphous Layers ...................................... 361
16.2.1 Amorphous Ice on Metal Surfaces ................ 363
16.2.2 Amorphous NH3 on Cu(lll) ....................... 369
16.3 Ultrafast Trapping and Ultraslow Stabilization of
Electrons in Crystalline Solvents ..................... 372
16.3.1 Crystalline Ice on Ru(001) ..................... 372
16.3.2 Reactivity of Trapped Electrons on Ice ......... 376
16.4 Conclusion ............................................ 377
References ................................................. 378
Part Four Photoinduced Modification of Materials and
Femtochemistry ................................................ 381
17 Theory of Femtochemistry at Metal Surfaces: Associative
Molecular Photodesorption as a Case Study .................. 383
Peter Saalfrank, Tillmann Klamroth, Tijo Vazhappilly, and
Rigoberto Hernandez
17.1 Introduction .......................................... 383
17.2 Theory of Femtochemistry at Surfaces .................. 385
17.2.1 Weakly Nonadiabatic Models ..................... 385
17.2.1.1 Two-and Three-Temperature Models ...... 385
17.2.1.2 One-Dimensional Classical,
Arrhenius-Type Models ................. 387
17.2.1.3 Langevin Dynamics with Electronic
Friction .............................. 388
17.2.1.4 Quantum Treatment with Master
Equations ............................. 389
17.2.2 Strongly Nonadiabatic Dynamics ................. 390
17.2.2.1 Multistate Time-Dependent
Schrödinger Equation .................. 390
17.2.2.2 Open-System Density Matrix Theory ..... 390
17.2.2.3 Stochastic Wave Packet Approaches ..... 393
17.2.2.4 Quantum-Classical Hopping Schemes ..... 394
17.3 Femtosecond-Laser Driven Desorption of H2 and D2
from Ru(0001) ......................................... 395
17.3.1 Experimental Facts ............................. 395
17.3.2 Potentials, Electronic Lifetime, and
Friction ....................................... 395
17.3.2.1 The Ground-State Potential and
Vibrational Levels .................... 395
17.3.2.2 The Excited-State Potential and
Electronic Lifetime ................... 396
17.3.2.3 Frictional Surfaces and Vibrational
Relaxation ............................ 397
17.3.3 DIMET at a Single Laser Fluence ................ 399
17.3.3.1 Langevin Dynamics Approach ............ 399
17.3.3.2 Stochastic Wave Packet Approach ....... 401
17.3.4 Scaling of DIMET with Laser Fluence ............ 402
17.4 Conclusions ........................................... 404
References ................................................. 405
18 Time-Resolved Investigation of Electronically Induced
Diffusion Processes ........................................ 409
Jens Güdde, Mischa Bonn, Hiromu Ueba, and Ulrich Höfer
18.1 Introduction .......................................... 409
18.2 Detection of Electronically Induced Diffusion ......... 410
18.2.1 Time-Resolved Techniques ....................... 411
18.2.2 Second Harmonic Generation ..................... 412
18.2.3 Time-Resolved Sum-Frequency Generation ......... 414
18.3 Description of Electronically Induced Motion by
Electronic Friction ................................... 415
18.3.1 Electronic Friction Models ..................... 415
18.3.2 Generalized Description of Heat Transfer at
Surfaces ....................................... 418
18.4 Results ............................................... 426
18.4.1 O/Pt(lll) ...................................... 426
18.4.2 CO/Pt(533) ..................................... 434
18.4.2.1 Numerical Results of CO Hopping on
a Pt (553) Surface .................... 439
18.4.2.2 Two-Pulse Correlation Measurements .... 440
18.5 Summary ............................................... 441
References ................................................. 442
19 Laser-Induced Softening of Lattice Vibrations .............. 447
Eeuwe S. Zijlstra and Martin E. Garcia
19.1 Introduction .......................................... 447
19.2 Theoretical Framework ................................. 448
19.2.1 The Hamiltonian of the Solid ................... 448
19.2.2 Born-Oppenheimer Approximation ................. 449
19.2.2.1 General Solution of Ĥ ................. 450
19.2.2.2 Adiabatic Approximation ............... 450
19.2.3 Properties of Ĥ0 ............................... 451
19.2.4 Phonons in the Ground-State Potential Energy
Surface ........................................ 452
19.2.5 Electron-Phonon Coupling and Excitation of
Coherent Phonons in the Ground-State
Potential Energy Surface ....................... 453
19.2.6 "Laser Excited" Potential Energy Surfaces ...... 454
19.2.7 Displacive Excitation of Coherent Phonons.
Phonon Softening ............................... 457
19.2.8 Comparison to Other Theories for the
Generation of Coherent Phonons ................. 457
19.3 Laser-Induced Events Involving Phonon Softening ....... 458
19.3.1 The A7 Structure ............................... 459
19.3.2 Ultrafast Electron-Hole Thermalization in
Bismuth ........................................ 461
19.3.3 Amplitude Collapse and Revival of Coherent
Alg Phonons in Bismuth: A Classical
Phenomenon? .................................... 464
19.3.4 Laser-Induced Phonon-Phonon Interactions in
Bismuth ........................................ 465
19.3.5 Ultrafast Laser-Induced Solid-to-Solid
Transition in Arsenic Under Pressure ........... 466
19.3.6 The Zinc-Blende Structure. Ultrafast Melting
of InSb ........................................ 468
19.4 Conclusion ............................................ 471
References ................................................. 471
20 Femtosecond Time- and Angle-Resolved Photoemission as a
Real-time Probe of Cooperative Effects in Correlated
Electron Materials ......................................... 475
Patrick S. Kirchmann, Luca Petfetti, Martin Wolf, and Uwe
Bovensiepen
20.1 Introduction .......................................... 475
20.2 Hot Electron Relaxation ............................... 477
20.3 Photoinduced Insulator-Metal Transitions .............. 480
20.3.1 Response of 1T-TaS2 to Optical Excitation ...... 480
20.3.2 Dynamics of a Photoinduced Melting of a
Charge Density Wave in TbTe3 ................... 485
20.3.2.1 Electronic Band Structure of TbTe3 in
Thermal Equilibrium ................... 486
20.3.2.2 Weak Perturbation Regime .............. 487
20.3.2.3 Strong Perturbation Regime ............ 490
20.3.2.4 Assignment of the Collective Modes .... 490
20.3.2.5 Ultrafast Melting of the CDW State .... 491
20.4 Discussion ............................................ 494
20.5 Conclusions and Outlook ............................... 495
References ................................................. 496
Part Five Recent Developments and Future Directions .......... 499
21 Time-Resolved Photoelectron Spectroscopy at Surfaces Using
Femtosecond XUV Pulses ..................................... 501
Stefan Mathias, Michael Bauer, Martin Aeschlimann, Luis
Miaja-Avila, Henry C. Kapteyn, and Margaret M, Murnane
21.1 Introduction .......................................... 501
21.2 Femtosecond XUV Sources ............................... 503
21.2.1 High Harmonic Generation ....................... 503
21.2.2 Free Electron Laser ............................ 507
21.3 Photoelectron Spectroscopy Using XUV Pulses: Some
Technical Aspects ..................................... 510
21.3.1 Time-Resolved PES and Angle-Resolved PES ....... 510
21.3.1.1 Experimental Setup .................... 510
21.3.1.2 Wavelength Selection .................. 512
21.3.2 XUV Pulse Profile Characterization ............. 514
21.3.3 Efficient Detection Schemes for XUV Time- and
Angle-Resolved Photoemission ................... 515
21.3.4 Space Charge Effects ........................... 517
21.4 Review of Pioneering Experiments ...................... 519
21.4.1 Static Photoelectron Spectroscopy Using High
Harmonic Sources ............................... 519
21.4.2 Time-Resolved Photoemission Using XUV Pulses ... 521
21.4.2.1 Probing Electron Excitations .......... 521
21.4.2.2 Time-Resolved Valence and Core-Level
Spectroscopy .......................... 523
21.4.2.3 Laser-Assisted Photoelectric Effect
From Surfaces ......................... 525
21.4.2.4 FEL-Based Time-Resolved
Photoemission: First Results .......... 528
21.5 Conclusions and Outlook ............................... 530
References ................................................. 530
22 Attosecond Time-Resolved Spectroscopy at Surfaces .......... 537
Adrian L Cavalieri, Ferenc Krausz, Ralph Ernstorfer,
Reinhard Kienberger, Peter Feulner, Johannes V. Barth,
and Dietrich Menzel
22.1 Overview .............................................. 537
22.2 Examples for Ultrafast Dynamics on Solid Surfaces ..... 538
22.2.1 Electronic Response ............................ 538
22.2.2 Charge Transfer Dynamics and Resonant
Photoemission .................................. 539
22.2.3 Scattering Experiments and Band Structure
Buildup ........................................ 542
22.3 Attosecond Experiments at Surfaces .................... 542
22.3.1 General Remarks ................................ 542
22.3.2 Principles of Surface-Related Attosecond
Metrology ...................................... 543
22.3.3 Generation of Isolated Attosecond Pulses and
Principle of Attosecond Spectroscopy of
Solids ......................................... 543
22.3.4 Hardware Requirements .......................... 544
22.3.5 First Experimental Results ..................... 545
22.3.6 Future Experiments ............................. 549
22.3.6.1 Improving the Theoretical
Description of Streaking Experiments
on Solid Targets ...................... 549
22.3.6.2 Dynamics of Band Structure
Formation, Screening, and Magnetic
Effects ............................... 549
22.3.6.3 Charge Transport ...................... 551
References ................................................. 552
23 Simultaneous Spatial and Temporal Control of Nanooptical
Fields ..................................................... 555
Walter Pfeiffer and Martin Aeschlimann ..................... 555
Introduction ............................................... 555
23.2 Optical Near-Field Control via Polarization Pulse
Shaping ............................................... 558
23.3 Experimental Demonstration of Spatiotemporal
Control ............................................... 562
23.3.1 РЕЕМ ........................................... 563
23.3.2 РЕЕМ as a Near-Field Probe ..................... 564
23.3.3 Time-Resolved РЕЕМ ............................. 566
23.3.4 Polarization Pulse Shaping ..................... 569
23.3.5 Adaptive Optimization of Nanoscale Nonlinear
Photoemission Patterns ......................... 569
23.3.6 Simultaneous Spatial and Temporal Control of
Optical Near Fields ............................ 571
23.4 Future Prospects and Conclusions ...................... 573
References ................................................. 574
24 Coherently Controlled Electrical Currents at Surfaces ...... 579
Jens Güdde, Marcus Rohleder, Torsten Meier, Stephan
W. Koch, and Ulrich Höfer
24.1 Introduction .......................................... 579
24.2 Observation of Coherently Controlled Currents by
Photoelectron Spectroscopy ............................ 581
24.3 Modeling of the Coherent Excitation ................... 584
24.4 Time-Resolved Observation of Current Decay ............ 587
24.5 Summary ............................................... 588
References ................................................. 589
25 Ultrabroadband Terahertz Studies of Correlated Electrons ... 593
Rupert Huber and Alfred Leitenstorfer
25.1 Introduction .......................................... 593
25.2 Phase-Locked Few-Cycle THz Pulses: From
Ultrabroadband to High Intensity ...................... 594
25.3 Ultrafast Insulator-Metal Transition of VO2 ........... 599
25.4 THz Coherent Control of Excitons ...................... 605
25.5 Conclusions and Perspectives .......................... 609
References ................................................. 610
Index ...................................................... 615
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