Attosecond Nanophysics E-Book

• Herausgeber: Wiley-VCH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 707

Veröffentlichungsjahr: 2014

Beschreibung

The first broad and in-depth overview of current research in attosecond nanophysics, covering the field of active plasmonics via attosecond science in metals and dielectrics to novel imaging techniques with the highest spatial and temporal resolution.
The authors are pioneers in the field and present here new developments and potential novel applications for ultra-fast data communication and processing, discussing the investigation of the natural timescale of electron dynamics in nanoscale solid state systems.
Both an introduction for starting graduate students, as well as a look at the current state of the art in this hot and emerging field.

Leseprobe

Table of Contents

Cover

Related Titles

Title Page

Copyright

List of Contributors

Preface

Chapter 1: Introduction

1.1 Attosecond Tools

1.2 Solids in Strong Fields

1.3 Attosecond Physics in Isolated Nanosystems

1.4 Attosecond Physics on Nanostructured Surfaces

1.5 Perspectives

References

Chapter 2: Nano-Antennae Assisted Emission of Extreme Ultraviolet Radiation

2.1 Introduction and Motivation

2.2 Experimental Idea

2.3 High-Order Harmonic Generation

2.4 Plasmonics in Intense Laser Fields

2.5 Experiments

2.6 Conclusion and Outlook

References

Chapter 3: Ultrafast, Strong-Field Plasmonic Phenomena

3.1 Introduction

3.2 Ultrafast Photoemission and Electron Acceleration in Surface Plasmon Fields

3.3 Research on Surface Plasmon-Enhanced Photoemission and Electron Acceleration

3.4 Conclusions

Acknowledgments

References

Chapter 4: Ultrafast Dynamics in Extended Systems

4.1 Introduction—Why Ultrafast Electron Dynamics in Extended Systems?

4.2 Multi-Photon Absorption in Extended Systems

4.3 Coulomb Complexes: A Simple Approach to Ultrafast Electron Dynamics in FEL-Irradiated Extended Systems

4.4 Nano-Plasma Transients on the Femtosecond Scale

4.5 Summary

4.6 Acknowledgments

References

Chapter 5: Light Wave Driven Electron Dynamics in Clusters

5.1 Introduction

5.2 Resolving Light-Matter Interactions on the Atomic-Scale

5.3 Fundamentals of the Microscopic Particle-in-Cell Approach

5.4 Microscopic Analysis of Laser-Driven Nanoclusters

5.5 Conclusions

References

Chapter 6: From Attosecond Control of Electrons at Nano-Objects to Laser-Driven Electron Accelerators

6.1 Attosecond Control of Electrons at Nanoscale Metal Tips

6.2 Experiments on Dielectric Nanospheres

6.3 The Influence of the Spatial Field Distribution on Photoelectron Spectra

6.4 Time Resolved Pump-Probe Schemes

6.5 Electron Acceleration with Laser Light at Dielectric Nano-Gratings

References

Chapter 7: Theory of Solids in Strong Ultrashort Laser Fields

7.1 Interaction of Ultrafast Laser Pulse with Solids: Coherent and Incoherent Electron Dynamics

7.2 One Dimensional Tight Binding Model

7.3 3D Model of Electron Dynamics

References

Chapter 8: Controlling and Tracking Electric Currents with Light

8.1 Introduction

8.2 Electric Field Control of Currents: From the Vacuum Tube to the Transistor

8.3 Generating Electric Currents with Light: An Ultrabroad-Bandwidth Control Tool

8.4 Optical Field Control of Electric Current in Large Bandgap Materials

8.5 Attosecond Probing of the Strong-Field-Induced Changes of the Dielectric Electronic Properties

8.6 Detection of the Carrier-Envelope Phase Using Optical-Field-Induced Currents

8.7 Toward Ultrafast Photoactive Logic Circuits?

References

Chapter 9: Ultrafast Nano-Focusing for Imaging and Spectroscopy with Electrons and Light

9.1 Introduction

9.2 Adiabatic Nanofocusing

9.3 Nanometer-Sized Localized Electron Sources

9.4 Summary and Conclusion

Acknowledgments

References

Chapter 10: Imaging Localized Surface Plasmons by Femtosecond to Attosecond Time-Resolved Photoelectron Emission Microscopy – “ATTO-PEEM”

10.1 Introduction

10.2 Time-Resolved Multiphoton PEEM with Femtosecond Time Resolution

10.3 The “ATTO-PEEM”

References

Index

End User License Agreement

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Guide

Cover

Table of Contents

Preface

Chapter 1: Introduction

List of Illustrations

Figure 1.1

Figure 1.2

Figure 1.3

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.8

Figure 2.5

Figure 2.6

Figure 2.7

Figure 2.9

Figure 2.12

Figure 2.10

Figure 2.11

Figure 2.13

Figure 2.14

Figure 2.15

Figure 2.16

Figure 3.1

Figure 3.2

Figure 3.3

Figure 3.4

Figure 3.5

Figure 3.6

Figure 3.7

Figure 3.8

Figure 3.9

Figure 3.10

Figure 3.11

Figure 3.12

Figure 3.13

Figure 3.14

Figure 3.15

Figure 3.16

Figure 3.17

Figure 3.18

Figure 3.19

Figure 3.20

Figure 3.21

Figure 3.22

Figure 3.23

Figure 3.24

Figure 3.25

Figure 3.26

Figure 3.27

Figure 3.28

Figure 4.1

Figure 4.2

Figure 4.3

Figure 4.4

Figure 4.5

Figure 4.6

Figure 4.7

Figure 4.8

Figure 4.11

Figure 4.9

Figure 4.10

Figure 4.12

Figure 4.13

Figure 4.15

Figure 4.16

Figure 4.17

Figure 4.14

Figure 5.1

Figure 5.2

Figure 5.3

Figure 5.4

Figure 5.5

Figure 5.6

Figure 5.7

Figure 5.8

Figure 5.9

Figure 5.10

Figure 5.11

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4

Figure 6.5

Figure 6.6

Figure 6.7

Figure 6.8

Figure 6.9

Figure 6.10

Figure 6.11

Figure 6.12

Figure 6.13

Figure 6.14

Figure 6.15

Figure 6.16

Figure 6.17

Figure 6.18

Figure 6.19

Figure 6.20

Figure 6.21

Figure 6.22

Figure 6.23

Figure 6.24

Figure 7.1

Figure 7.2

Figure 7.3

Figure 7.4

Figure 7.5

Figure 7.6

Figure 7.7

Figure 7.8

Figure 7.9

Figure 7.10

Figure 7.11

Figure 7.12

Figure 7.13

Figure 7.14

Figure 7.15

Figure 7.16

Figure 7.17

Figure 8.1

Figure 8.2

Figure 8.3

Figure 8.4

Figure 8.5

Figure 8.6

Figure 8.7

Figure 8.8

Figure 8.9

Figure 8.10

Figure 8.11

Figure 8.12

Figure 8.13

Figure 8.14

Figure 8.15

Figure 9.1

Figure 9.2

Figure 9.3

Figure 9.4

Figure 9.5

Figure 9.6

Figure 9.7

Figure 9.8

Figure 9.9

Figure 9.10

Figure 9.11

Figure 9.12

Figure 9.13

Figure 9.14

Figure 9.15

Figure 9.16

Figure 9.17

Figure 9.18

Figure 9.19

Figure 9.20

Figure 9.21

Figure 10.1

Figure 10.2

Figure 10.3

Figure 10.4

Figure 10.5

Figure 10.6

Figure 10.7

Figure 10.8

Figure 10.9

Figure 10.10

Figure 10.11

Figure 10.12

Figure 10.13

Figure 10.14

Figure 10.15

Figure 10.16

Figure 10.17

Figure 10.18

Figure 10.19

Figure 10.20

Figure 10.21

Figure 10.22

Figure 10.23

Figure 10.24

List of Tables

Table 2.1

Table 7.1

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Edited by

Peter Hommelhoff

Matthias F. Kling

Attosecond Nanophysics

From Basic Science to Applications

Editors

Prof. Peter Hommelhoff

Friedrich-Alexander-Universität Erlangen-Nürnberg

Erlangen, Germany

Prof. Matthias F. Kling

Ludwig-Maximilians-Universität München

Garching, Germany

Cover

Laser light pulses consisting of a few optical cycles are focused onto a nanometric metal tip. Owing to the high intensity electrons are emitted on a very short time scale by highly non-linear photon absorption. Due to plasmonic effects the actual laser intensity is further increased at the tip's apex.

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The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <http://dnb.d-nb.de>.

© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Boschstr. 12, 69469 Weinheim, Germany

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List of Contributors

Vadym Apalkov

Georgia State University

Department of Physics and Astronomy

Atlanta, Georgia 30303

USA

Fernando Ardana

Paul Scherrer Institut

Villigen PSI

Switzerland

Cord L. Arnold

Department of Physics

Lund University

Lund

Sweden

Thomas Brabec

University of Ottawa

Centre for Research in Photonics

Department of Physics

Ottawa K1N6N5

Canada

Soo Hoon Chew

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

Péter Dombi

Wigner Research Centre for Physics

1MTA “Lendület” Ultrafast Nanooptics Group

Konkoly-Thege M. ù 29-33

Budapest

Hungary

and

Max Planck Institute of Quantum Optics

Garching

Germany

Abdulhakem Y. Elezzabi

University of Alberta

Department of Electrical and Computer Engineering

Edmonton

AB T6G 2V4

Canada

Thomas Fennel

University of Rostock

Institute of Physics

Rostock

Germany

Alexander Guggenmos

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

Chen Guo

Department of Physics

Lund University

Lund

Sweden

Peter Hommelhoff

Department of Physics

Friedrich-Alexander-Universität Erlangen-Nürnberg

D-91058 Erlangen

Germany

and

Max Planck Institute of Quantum Optics

D-85748 Garching

Germany

Ulf Kleineberg

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

and

Max Planck Institute of Quantum Optics

D-85748 Garching

Germany

Matthias F. Kling

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

and

Max Planck Institute of Quantum Optics

D-85748 Garching

Germany

Milutin Kovacev

Leibniz Universität Hannover

Institute of Quantum Optics

Welfengarten 1

Hannover

Germany

Anne L'Huillier

Department of Physics

Lund University

Lund

Sweden

Christoph Lienau

Carl von Ossietzky Universität Oldenburg

Institut für Physik

Oldenburg

Germany

and

Carl von Ossietzky Universität Oldenburg

Center of Inferface Science

Oldenburg

Germany

Eleonora Lorek

Department of Physics

Lund University

Lund

Sweden

Erik Mårsell

Department of Physics

Lund University

Lund

Sweden

Johan Mauritsson

Department of Physics

Lund University

Lund

Sweden

Anders Mikkelsen

Department of Physics

Lund University

Lund

Sweden

Miguel Miranda

Department of Physics

Lund University

Lund

Sweden

Uwe Morgner

Leibniz Universität Hannover

Institute of Quantum Optics

Welfengarten 1

Hannover

Germany

Monika Noack

Leibniz Universität Hannover

Institute of Quantum Optics

Welfengarten 1

Hannover

Germany

Tim Paasch-Colberg

Max Planck Institute of Quantum Optics

Division of Attosecond Physics

D-85748 Garching

Germany

Kellie Pearce

Max Planck Institute of Quantum Optics

D-85748 Garching

Germany

Christian Peltz

University of Rostock

Institute of Physics

Rostock

Germany

Nils Pfullmann

Leibniz Universität Hannover

Institute of Quantum Optics

Welfengarten 1

Hannover

Germany

Markus Raschke

University of Colorado

Department of Physics, and JILA

Boulder, CO 80303

USA

Carsten Reinhardt

Laser Zentrum Hannover e. V.

Hollerithallee 8

Hannover

Germany

Claus Ropers

University of Göttingen

4th Physical Institute

Göttingen

Germany

Jan-Michael Rost

Max Planck Institute for the Physics of Complex Systems

Department Finite Systems

Dresden

Germany

Piotr Rudawski

Department of Physics

Lund University

Lund

Sweden

and

Max Planck Institute of Quantum Optics

D-85748 Garching

Germany

Ulf Saalmann

Max Planck Institute for the Physics of Complex Systems

Department Finite Systems

Dresden

Germany

Agustin Schiffrin

Max Planck Institute of Quantum Optics

Division of Attosecond Physics

Hans-Kopfermann-Straße 1

D-85748 Garching

Germany

and

University of British Columbia

Department of Physics and Astronomy

Agricultural Road

Vancouver, V6T 1Z1

Canada

and

University of British Columbia

Quantum Matter Institute

East Mall

Vancouver, V6T 1Z4

Canada

and

Monash University

School of Physics

PO Box 27

Building 19 North

Clayton

Victoria 3800

Australia

Jürgen Schmidt

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

Martin Schultze

University of California

Department of Chemistry

D60 Hildebrand Hall

Berkeley, 94720

USA

and

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

Christian Späth

Ludwig-Maximilians-Universität München

Department of Physics

Am Coulombwall 1

D-85748 Garching

Germany

Brady C. Steffl

Kansas-State University

Department of Physics

J.R Macdonald Laboratory

Manhattan, KS-66506

USA

Mark I. Stockman

Georgia State University

Department of Physics and Astronomy

Atlanta, Georgia 30303

USA

Frederik Süßmann

Max Planck Institute of Quantum Optics

D-85748 Garching

Germany

Charles Varin

University of Ottawa

Centre for Research in Photonics

Department of Physics

K1N6N5 Ottawa

Canada

Preface

This book establishes that attosecond nanophysics has become an important subdiscipline of attosecond science, but the fact that it is the first of its kind also indicates the relative youth of this field. Even so, a bright future can be foreshadowed by the link between the time and length scales that play a role in nanomaterials and their applications: the fastest electronic processes in nanomaterials occur on timescales in the attosecond domain.

We are grateful to the authors for their contributions and to the many colleagues that were involved in the research discussed here. We further gratefully acknowledge support by Friedrich-Alexander-Universität Erlangen-Nürnberg, Ludwig-Maximilians-Universität München, Kansas-State University, Max Planck Institute of Quantum Optics, the German Research Foundation via the cluster of excellence “Munich Center for Advanced Photonics (MAP)”, the US Department of Energy and last but not least the four companies that facilitated the color version of this book.

1Introduction

Matthias F. Kling, Brady C. Steffl and Peter Hommelhoff

The generation of attosecond (1 as = 10−18 s) laser pulses in 2001 [1, 2] gave birth to attosecond physics, a field that continues to see rapid development [3]. The field was initially dominated by studies of electron/nuclear dynamics in atoms, molecules, and solids; however, the field has matured to include studies of nanomaterials. Ultrashort, intense light pulses with a well controlled electric-field waveform have enabled the generation of isolated attosecond light pulses [4]. Interaction of such fields with solids and nanomaterials leads to ultrafast nonlinear phenomena and dynamics and is an important research direction in attosecond nanophysics; a variety of such nonlinear and ultrafast phenomena are discussed in this book. In this chapter, we outline common photonic tools and the principle phenomena that can be used to study them. We also indicate where they are discussed in the text.

1.1 Attosecond Tools

The attosecond physics community has developed a few photonic tools to control and trace electron dynamics in matter. Two of the most important photonic tools have been applied in studies in this book and are briefly introduced. These tools are light pulses with a controlled waveform and attosecond light pulses.

1.1.1 Strong Field Control Using Laser Pulses with Well-Defined Waveforms

There are many degrees of control over laser pulses – frequency, wavelength, pulse duration, and intensity are straightforward and readily accessible parameters – but access to the carrier envelope phase (CEP) provides another (extremely precise) degree of control. The CEP is the offset of the maximum of the carrier wave relative to the maximum of the pulse envelope (Figure 1.1) and impacts many areas of ultrafast physics. In particular, when individual laser pulses last only a few optical cycles, the CEP becomes extremely relevant. In these cases, a variation of the waveform of the laser pulse (e.g., by changing the CEP) may significantly alter the outcome of an experiment.

Figure 1.1 Few-cycle light fields with a controlled waveform. A few-cycle pulse (pulse duration 2.7 fs) at 800 nm with three different CEPs (red: ϕ = 0, green: ϕ = π, and blue: ϕ = π/2). The pulse envelope is shown as a black line.

Additionally, control over the CEP (ϕ) allows for the sculpting of optical waveforms: Fourier synthesis of waves with certain phases over a broad range of frequencies may result in non-sinusoidal electric-field waveforms, such as sawtooth or square waveforms. Such waveforms are well known in conventional electronics; however, in conventional electronics, these correspond to gigahertz frequencies, while optical light fields reach the petahertz (PHz) domain. Ultimately, such sculpted fields – similar to conventional electronics – will permit the control of electrons with the highest possible speed. Such control of electronic phenomena in nanomaterials on attosecond timescales would correspond to electronics operating at petahertz frequencies. The rapid development of this control is exemplified in several chapters in this book.

1.1.2 Attosecond Light Pulses: Tracing Electron Dynamics

Attosecond light pulses in the extreme ultraviolet (XUV) spectral range can be generated via high-harmonic generation (HHG). HHG is commonly described as a three-step process [5, 6] (Figure 1.2) where a strong laser field first tunnel ionizes an atom or molecule (step 1), then the emitted electron is accelerated in the laser field (step 2) and finally, an XUV photon is created upon the recollision and recombination of the electron with the ion (step 3). HHG was first observed with atomic neon in 1992 [7] and has facilitated tabletop sources of coherent XUV and soft X-ray radiation [3, 8]. These novel sources find applications in time-resolved studies of electron and nuclear dynamics in atoms, molecules, nanostructures, and solids [3, 9–13].

Figure 1.2 Illustration of the three-step high-harmonic generation process. Step 1, as demarcated by the black number, shows a strong laser field tunnel-ionizing an atom or molecule. Step 2 shows the electron being accelerated in the strong-laser field, and step 3 shows the higher-energy electron recombining with the core. This step causes the emission of an XUV photon.

While HHG is a coherent process that can lead to the generation of attosecond light pulses, incoherent XUV light emission might occur through fluorescence. In conventional attosecond pulse generation, a dense target and suitable phase-matching conditions can render incoherent processes negligible; however, typically a high-power laser system is required to drive the coherent process. As Chapter 2 by Pfullmann et al. describes, the generation of sufficiently strong fields for the generation of XUV light can also involve nanoscopic field enhancement in the near-fields of (coupled) nanostructures.

1.2 Solids in Strong Fields

The picture of the driven electron (wavefunction) recolliding with the parent atom has been broadly used to explain the underlying physics of a plethora of gas-phase experiments with atoms and molecules, as well as for semi-infinite boundaries such as those of nanospheres and nanostructures. However, inside solids another picture has to be developed to reflect the very different environment that the driven electronic matter (wave) experiences, (i.e., compared to a vacuum in the former case). First experiments on the generation of HHG inside solids have indicated a different laser intensity scaling behavior, which underlines the need for a new physical picture [14]. We note in passing that even inside solids the recolliding electron picture has been successfully employed to explain high-order sideband generation and has elucidated exciton dynamics of electron–hole pairs in semiconductor quantum wells driven with terahertz fields [15].

Discussions of these topics can be found in Chapter 7. Apalkov and Stockman discuss what happens to solids when they are exposed to strong laser fields. Wannier-Stark localization [16, 17] at optical field strengths can take place, which can dramatically alter the nature of the material. For example, a metal can be changed into a semiconductor, or even into a dielectric, depending on the field strength. Here, the opposite can also hold true: a dielectric can be turned into a conductor or semiconductor. In Chapter 8, initial experimental results along these lines are discussed. Schiffrin, Paasch-Colberg, and Schultze show that the resistance inside a transparent dielectric structure can be altered to an extent that its resistance indicates semiconducting behavior. It is fascinating to consider that this only holds while the optical field is large, that is, the time scale is much shorter than that of the optical period.

1.3 Attosecond Physics in Isolated Nanosystems

Isolated nanosystems, such as clusters, nanoparticles, and nanotips are ideal model systems for attosecond studies on the nanoscale; complex multi-electron physics can be explored under well defined conditions. In all cases, the intense field can excite collective electron dynamics. Plasmons are example of collective excitations in nanosystems at metal surfaces where conduction electrons excited by the incident light's electromagnetic field (typically ultraviolet to the visible range) oscillate collectively [18]. Plasmons are currently being explored in many directions: to increase sensitivity of optical probes [19], as single photon emission sources [20], for use in nanophotonic devices with smaller-than-conventional optical circuits, [21] and even in medical applications [22]. The plasmonic response of materials can change drastically with only small changes to the metal nanoparticle or surrounding dielectric. This high sensitivity is largely responsible for many applications of plasmonic nanomaterials in sensing and spectroscopy.

Figure 1.3a depicts how the laser wave excites a plasmon in a nanoparticle– here a gold nanosphere. When the laser field is applied to the nanoparticle, it drives the conduction electrons collectively. This creates a strong, oscillating dipole: the plasmon. In isolated nanostructures these plasmons are localized surface plasmons (LSPs). Their eigenfrequencies depend on the composition, size, and shape of the nanostructure [18] as well as the surrounding dielectric. Plasmons can also propagate along metal-dielectric interfaces as surface plasmon polaritons (SPPs). SPPs decay exponentially into the dielectric and form an evanescent field (Figure 1.3b). The excitation of SPPs requires the matching of the light and the SPP's k-vectors, which can be achieved (e.g., by gratings that are carved into the metal surface) as illustrated in Chapter 9 for metal nanotips by Lienau, Raschke, and Ropers. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy, and bio-photonics [19]. Propagating plasmons are of particular interest to the development of ultrafast electronics since they reach speeds close to the vacuum speed of light and can transfer information on length scales well below the diffraction limit.

Figure 1.3 Representation of plasmonic excitation at metal-dielectric interfaces. (a) The laser's oscillatory electric field causes an oscillatory motion of the conduction electrons (localized surface plasmon) in a nanoparticle. (b) On extended surfaces, surface plasmon polaritons are formed that can propagate along the metal-dielectric interface.

Süßmann et al. describe the CEP-controlled electron emission from metallic nanotips and dielectric nanoparticles in intense, few-cycle laser fields in Chapter 6. The emitted electrons experience the enhanced near-fields of the nanostructures and are accelerated to energies exceeding the atomic cutoff for backscattered electrons. The measured cutoff can in turn serve as a measure of the field-enhancement. At longer, mid-infrared wavelengths the electron can leave the near-field of the nanosystem in a fraction of the laser-driven oscillations – this interesting regime is discussed in Chapter 9. Finally, Chapter 6 shows that dielectric nanostructures can be used to drive laser acceleration of electrons to an entirely new level, approaching acceleration gradients in the giga-electron volt per meter range and opening the door to optical electron accelerators – on a chip.

At intensities where multiple ionization occurs within an intense laser pulse, charge interaction becomes important. This is theoretically discussed in Chapter 4 by Saalmann and Rost for cases where the light interaction is so strong that the nanomatter is converted into a nanoplasma. The chapter shows that the complex dynamics of such transient nanoplasmas can be resolved with attosecond tools. When the diameter of a nanoparticle approaches the excitation wavelength, propagation of the light inside the particle has to be taken into account. Varin et al. introduce a new theoretical approach in Chapter 5, the microscopic particle-in-cell (MicPIC) simulations, that can treat the interaction of light with large nanosystems and at high intensities with the accuracy of a microscopic model. The simulations can be applied in strong near-IR or extreme-ultraviolet photoemission of clusters and large nanoparticles and offer new opportunities for modeling time-dependent diffraction studies using free-electron lasers.

1.4 Attosecond Physics on Nanostructured Surfaces

Nanostructured surfaces offer increased complexity and ultimately the ability to build nanophotonic devices with new functionalities. Of particular interest are plasmonic nanosystems. SPPs can travel short distances along a metal nanofilm, be coupled into nanotips (Chapter 9), and propagate through a nanowire [20] or along nanostructured surfaces (Chapter 10). Importantly, using the principle of adiabatic focusing [23] SPPs can be focused much below the diffraction limit, leading to extreme enhancement of fields locally. Because the dispersion of the propagating plasmon can be measured and controlled, it is even feasible to maintain an ultrashort pulse duration at the apex of a tip. This enables researchers to expose localized nanostructures on surfaces to femtosecond light pulses, certainly also with CEP control, in a nano-localized volume. The electron photoemission and acceleration and its CEP control from plasmonic nanostructured surfaces is discussed in Chapter 3 by Dombi and Elezzabi. High-energy electrons can be generated due to the field enhancement of coupled nanostructures.

Similarly, a corrugated surface leads to localized, large field-enhancement factors (hot spots). If the local fields are large enough, electrons are emitted from the hot spot. Chapter 10 by Chew et al. discusses attosecond photoemission electron microscopy (ATTO-PEEM) [11] as a new metrology that enables the measurement of the plasmonic fields of hot spots and of nanostructures on surfaces with both attosecond time and nanometer spatial resolution. The chapter describes the principal methodology and progress toward its implementation. The realization of the ATTO-PEEM would comprise a wholly new surface science technique that would be broadly applicable – from understanding plasmon behavior on its natural time scale to the understanding of molecular surface bond formation, for example.

The large field-enhancement factor of nanostructured surfaces is also at the center of attempts to generate XUV light at megahertz repetition rates. As already mentioned in Chapter 2, Pfullmann et al. report on the status of this enabling field. The idea is to fill the surface of a transparent material with structures that locally enhance the IR laser field such that XUV generation takes place even though the laser pulse energy is much smaller than in conventional schemes. The small interaction volume at the nanostructures is mitigated by the arrangement of as many nanostructures as possible, which is an easy task with today's nanofabrication capabilities.

1.5 Perspectives

Attosecond nanophysics is a rapidly developing field. The interaction of intense fields with (nanostructured) solids offers access to nonlinear phenomena, which enables ultrafast circuitry and ultimately petahertz electronics. Progress is fueled by the application of ultrashort pulses (of just a few cycles or even less), where damage to the nanostructures can be avoided even at high intensities. The studies in this book show that the resulting collective electron dynamics are highly controllable by the waveform of the optical field interacting with the nanostructures. If we recognize that field-driven electron motion is at the very basis of micro-electronics, the potential of light-field driven electron motion becomes obvious. But the impact that understanding the processes inside nanostructures on their inherent time scales could have is not limited to the topics mentioned earlier. Even sunlight harvesting through optical-antenna-enhanced solar cells might be implemented. We have already mentioned new time-resolved nanoscale imaging techniques and the in-depth understanding of plasma processes. With the help of dielectric nanostructures, new electron acceleration schemes come into reach that may one day enable the construction of small, laser-driven particle smashers. Today these machines are large and rely on particle accelerator development taken to extreme limits over many decades, so they are likely not replaced fast. However, close to 10 000 accelerators, each about a meter in size, are operational in hospitals in oncology departments – chip-scale photonics-based dielectric counterparts may take over at some point.

While already many real-world applications of attosecond nanophysics come to mind, this book focuses on the fundamental physics behind the various directions of this nascent field. The editors hope that the book will introduce unfamiliar readers to this new and fascinating area of physics and give an overview of the various research directions. Researchers in the field may obtain an overview of ongoing activities and potentially discover new links to related fields. We thank all authors for their excellent contributions and look forward to jointly discovering where attosecond nanophysics will take us.

References

1. Hentschel, M., Kienberger, R., Spielmann, C., Raider, G.A., Milosevic, N., Brabec, T., Corkum, P., Heinzmann, U., Drescher, M., and Krausz, F. (2001) Attosecond metrology.

Nature

,

414

, 509–513.

2. Paul, P.M., Toma, E.S., Breger, P., Mullot, G., Augé, F., Balcou, P., Muller, H.G., and Agostini, P. (2001) Observation of a train of attosecond pulses from high harmonic generation.

Science

,

292

, 1689–1692.

3. Krausz, F. and Ivanov, M. (2009) Attosecond physics.

Rev. Mod. Phys.

,

81

, 163–234.

4. Baltuska, A., Udem, T., Uiberacker, M., Hentschel, M., Goulielmakis, E., Gohle, C., Holzwarth, R., Yakovlev, V.S., Scrinzi, A., Hansch, T.W., and Krausz, F. (2003) Attosecond control of electronic processes by intense light fields.

Nature

,

421

, 611–615.

5. Corkum, P.B. (1993) Plasma perspective on strong-field multiphoton ionization.

Phys. Rev. Lett.

,

71

, 1994–1997.

6. Krause, J.L., Schafer, K.J., and Kulander, K.C. (1992) High-order harmonic generation from atoms and ions in the high intensity regime.

Phys. Rev. Lett.

,

68

, 3535–3538.

7. Balcou, P., Cornaggia, C., Gomes, A.S.L., Lompre, L.A., and Huillier, A.L. (1992) Optimizing high-order harmonic generation in strong fields.

J. Phys. B: At. Mol. Opt. Phys.

,

25

, 4467.

8. Calegari, F., Lucchini, M., Negro, M., Vozzi, C., Poletto, L., Svelto, O., Silvestri, S.D., Sansone, G., Stagira, S., and Nisoli, M. (2012) Temporal gating methods for the generation of isolated attosecond pulses.

J. Phys. B: At. Mol. Opt. Phys.

,

45

, 074002.

9. Schultze, M., Fieß, M., Karpowicz, N., Gagnon, J., Korbman, M., Hofstetter, M., Neppl, S., Cavalieri, A.L., Komninos, Y., Mercouris, T., Nocolaides, C.A., Pazourek, R., Nagele, S., Feist, J., Burgdörfer, J., Azzeer, A.M., Ernstorfer, R., Kienberger, R., Kleineberg, U., Goulielmakis, E., Krausz, F., and Yakovlev, V.S. (2010) Delay in photoemission.

Science

,

328

, 1658–1662.

10. Sansone, G., Kelkensberg, F., Perez-Torres, J.F., Morales, F., Kling, M.F., Siu, W., Ghafur, O., Johnsson, P., Swoboda, M., Benedetti, E., Ferrari, F., Lepine, F., Sanz-Vicario, J.L., Zherebtsov, S., Znakovskaya, I., L'Huillier, A., Ivanov, M.Y., Nisoli, M., Martin, F., and Vrakking, M.J.J. (2010) Electron localization following attosecond molecular photoionization.

Nature

,

465

, 763–766.

11. Stockman, M.I., Kling, M.F., Kleineberg, U., and Krausz, F. (2007) Attosecond nanoplasmonic-field microscope.

Nat. Photonics

,

1

, 539–544.

12. Cavalieri, A.L., Muller, N., Uphues, T., Yakovlev, V.S., Baltuska, A., Horvath, B., Schmidt, B., Blumel, L., Holzwarth, R., Hendel, S., Drescher, M., Kleineberg, U., Echenique, P.M., Kienberger, R., Krausz, F., and Heinzmann, U. (2007) Attosecond spectroscopy in condensed matter.

Nature

,

449

, 1029–1032.

13. Schultze, M., Bothschafter, E.M., Sommer, A., Holzner, S., Schweinberger, W., Fiess, M., Hofstetter, M., Kienberger, R., Apalkov, V., Yakovlev, V.S., Stockman, M.I., and Krausz, F. (2013) Controlling dielectrics with the electric field of light.

Nature

,

493

, 75–78.

14. Ghimire, S., DiChiara, A.D., Sistrunk, E., Agostini, P., DiMauro, L.F., and Reis, D.A. (2011) Observation of high-order harmonic generation in a bulk crystal.

Nat. Phys.

,

7

, 138–141.

15. Zaks, B., Liu, R.B., and Sherwin, M.S. (2012) Experimental observation of electron–hole recollisions.

Nature

,

483

, 580–583.

16. Wannier, G.H. (1960) Wave functions and effective Hamiltonian for Bloch electrons in an electric field.

Phys. Rev.

,

117

, 432–439.

17. Shockley, W. (1972) Stark ladders for finite, one-dimensional models of crystals.

Phys. Rev. Lett.

,

28

, 349–352.

18. Garcia, M.A. (2011) Surface plasmons in metallic nanoparticles: fundamentals and applications.

J. Phys. D Appl. Phys.

,

44

, 283001.

19. Barnes, W.L., Dereux, A., and Ebbesen, T.W. (2003) Surface plasmon subwavelength optics.

Nature

,

424

, 824–830.

20. Akimov, A.V., Mukherjee, A., Yu, C.L., Chang, D.E., Zibrov, A.S., Hemmer, P.R., Park, H., and Lukin, M.D. (2007) Generation of single optical plasmons in metallic nanowires coupled to quantum dots.

Nature

,

450

, 402–406.

21. Gramotnev, D.K. and Bozhevolnyi, S.I. (2010) Plasmonics beyond the diffraction limit.

Nat. Photonics

,

4

, 83–91.

22. Jain, S., Hirst, D.G., and O'Sullivan, J.M. (2012) Gold nanoparticles as novel agents for cancer therapy.

Br. J. Radiol.

,

85

, 101–113.

23. Stockman, M.I. (2004) Nanofocusing of optical energy in tapered plasmonic waveguides.

Phys. Rev. Lett.

,

93

, 137404.

2Nano-Antennae Assisted Emission of Extreme Ultraviolet Radiation

Nils Pfullmann, Monika Noack, Carsten Reinhardt, Milutin Kovacev and Uwe Morgner

2.1 Introduction and Motivation

Although plasmons are known for a long time [1], the field has rapidly developed throughout the last decade and a broad range of applications has emerged particularly for extreme light concentration [2]. For instance, nano-particles can be used to locally heat biological tissue, which has already found applications in novel methods of cancer therapy [3]. There, nano-particles are used to specifically destroy cancer cells without affecting the surrounding cells as in conventional approaches. Additionally, plasmons and nano-antennae in particular are a tool in nonlinear optics facilitating, for example, enhanced second harmonic generation [4]. Recent theoretical calculations even suggest the generation of isolated attosecond pulses, employing the nano-plasmonic field enhancement in ellipsoidal antennae [5]. Moreover, numerical simulations reveal the feasibility of attosecond plasmonic streaking [6].

This bridges the gap to a different rapidly growing field–namely high-order harmonic generation (HHG) in noble gases. The process was first observed roughly 20 years ago [7, 8] and has ever since provided a coherent light source in the extreme ultraviolet (EUV) spectral range. Due to the shorter wavelength, the pulse durations achieved have been pushed from the femtosecond into the attosecond regime [9]. Today, light pulses as short as 80 as can be generated [10] and a whole new field of physics has been opened up [11]. This unprecedented temporal resolution enables, among other things, new measurements in fundamental physics to study electron dynamics in atoms, molecules, and solid state materials.