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M Hofstetter,
A Aquila,
M Schultze,
A Guggenmos,
S Yang,
E Gullikson,
M Huth,
B Nickel,
J Gagnon,
V S Yakovlev,
E Goulielmakis,
F Krausz, U Kleineberg
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ABSTRACT: A novel multilayer material system consisting of lanthanum and molybdenum nano-layers for both broadband and highly reflecting multilayer mirrors in the energy range between 80 and 130 eV is presented. The simulation and design of these multilayers were based on an improved set of optical constants, which were recorded by extreme ultraviolet (XUV)/soft-x-ray absorption measurements on freestanding lanthanum nano-films between 30 eV and 1.3 keV. Lanthanum–molybdenum (La/Mo) multilayer mirrors were produced by ion-beam sputtering and characterized through both x-ray and XUV reflectivity measurements. We demonstrate the ability to precisely simulate and realize aperiodic stacks. Their stability against ambient air conditions is demonstrated. Finally, the La/Mo mirrors were used in the generation of single attosecond pulses from high-harmonic cut-off spectra above 100 eV. Isolated 200 attosecond-long pulses were measured by XUV-pump/IR-probe streaking experiments and characterized using frequency-resolved optical gating for complete reconstruction of attosecond bursts (FROG/CRAB) analyses.
New Journal of Physics 06/2011; 13(6):063038. · 4.18 Impact Factor
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E. Magerl,
S. Neppl,
A. L. Cavalieri,
E. M. Bothschafter,
M. Stanislawski,
Th. Uphues,
M. Hofstetter, U. Kleineberg,
J. V. Barth,
D. Menzel,
F. Krausz,
R. Ernstorfer,
R. Kienberger,
P. Feulner
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ABSTRACT: We describe an apparatus for attosecond photoelectron spectroscopy of solids and surfaces, which combines the generation of isolated attosecond extreme-ultraviolet (XUV) laser pulses by high harmonic generation in gases with time-resolved photoelectron detection and surface science techniques in an ultrahigh vacuum environment. This versatile setup provides isolated attosecond pulses with photon energies of up to 140 eV and few-cycle near infrared pulses for studying ultrafast electron dynamics in a large variety of surfaces and interfaces. The samples can be prepared and characterized on an atomic scale in a dedicated flexible surface science end station. The extensive possibilities offered by this apparatus are demonstrated by applying attosecond XUV pulses with a central photon energy of ∼125 eV in an attosecond streaking experiment of a xenon multilayer grown on a Re(0001) substrate.
Review of Scientific Instruments 06/2011; 82(6):063104-063104-6. · 1.37 Impact Factor
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M Schultze,
M Fiess,
N Karpowicz,
J Gagnon,
M Korbman,
M Hofstetter,
S Neppl,
A L Cavalieri,
Y Komninos,
Th Mercouris, [......],
S Nagele,
J Feist,
J Burgdörfer,
A M Azzeer,
R Ernstorfer,
R Kienberger, U Kleineberg,
E Goulielmakis,
F Krausz,
V S Yakovlev
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ABSTRACT: Photoemission from atoms is assumed to occur instantly in response to incident radiation and provides the basis for setting the zero of time in clocking atomic-scale electron motion. We used attosecond metrology to reveal a delay of 21 +/- 5 attoseconds in the emission of electrons liberated from the 2p orbitals of neon atoms with respect to those released from the 2s orbital by the same 100-electron volt light pulse. Small differences in the timing of photoemission from different quantum states provide a probe for modeling many-electron dynamics. Theoretical models refined with the help of attosecond timing metrology may provide insight into electron correlations and allow the setting of the zero of time in atomic-scale chronoscopy with a precision of a few attoseconds.
Science 06/2010; 328(5986):1658-62. · 31.20 Impact Factor
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M. Schultze,
M. Fiess,
N. Karpowicz,
J. Gagnon,
M. Korbman,
M. Hofstetter,
S. Neppl,
A. L. Cavalieri,
Y. Komninos,
Th. Mercouris, [......],
S. Nagele,
J. Feist,
J. Burgdorfer,
A. M. Azzeer,
R. Ernstorfer,
R. Kienberger, U. Kleineberg,
E. Goulielmakis,
F. Krausz,
V. S. Yakovlev
[show abstract]
[hide abstract]
ABSTRACT: Photoemission from atoms is assumed to occur instantly in response to incident radiation and provides the basis for setting the zero of time in clocking atomic-scale electron motion. We used attosecond metrology to reveal a delay of [IMG]f1.gif" ALT="Formula" BORDER="0"\textgreater} attoseconds in the emission of electrons liberated from the 2p orbitals of neon atoms with respect to those released from the 2s orbital by the same 100-electron volt light pulse. Small differences in the timing of photoemission from different quantum states provide a probe for modeling many-electron dynamics. Theoretical models refined with the help of attosecond timing metrology may provide insight into electron correlations and allow the setting of the zero of time in atomic-scale chronoscopy with a precision of a few attoseconds.
Science. 06/2010; 328:1658--1662.
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ABSTRACT: Mo/Si multilayer mirrors (30 periods, doublelayer thickness 7 nm) with the AZ-PF514 resist pattern whose smallest lines and spaces structure was 0.5 μm were etched by reactive ion etching (RIE) in a fluorinated plasma. The etch rate, selectivity and etch profile were investigated as a function of the gas mixture, pressure, and plasma rf power. The groove depth and the etch profile were investigated by an atomic force microscope before RIE, after RIE and after resist removal.
Chinese Physics Letters 08/2008; 16(9):665. · 0.73 Impact Factor
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E Goulielmakis,
M Schultze,
M Hofstetter,
V S Yakovlev,
J Gagnon,
M Uiberacker,
A L Aquila,
E M Gullikson,
D T Attwood,
R Kienberger,
F Krausz, U Kleineberg
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ABSTRACT: Nonlinear optics plays a central role in the advancement of optical science and laser-based technologies. We report on the confinement of the nonlinear interaction of light with matter to a single wave cycle and demonstrate its utility for time-resolved and strong-field science. The electric field of 3.3-femtosecond, 0.72-micron laser pulses with a controlled and measured waveform ionizes atoms near the crests of the central wave cycle, with ionization being virtually switched off outside this interval. Isolated sub-100-attosecond pulses of extreme ultraviolet light (photon energy approximately 80 electron volts), containing approximately 0.5 nanojoule of energy, emerge from the interaction with a conversion efficiency of approximately 10(-6). These tools enable the study of the precision control of electron motion with light fields and electron-electron interactions with a resolution approaching the atomic unit of time ( approximately 24 attoseconds).
Science 07/2008; 320(5883):1614-7. · 31.20 Impact Factor
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ABSTRACT: SummaryW/Si multilayers with 14 double layers (double layer spacing d = 24 nm) were deposited on Si [1001 substrates with hot-filament metal organic chemical vapor deposition (MOCVD). The layer thickness and growth was controlled by an in-situ X-ray reflectivity measurement. Cyclopentadienyl substituted silanes (C5Me5)Si2H5 and (C5Me4H)SiH3 were used as silicon precursors, while W(CO)6 was used for the tungsten deposition. The resulting multilayers were characterized by cross-section transmission electron microscopy (XTEM) and sputter auger electron spectroscopy (AES). In addition, the fragmentation of the silicon precursors was studied by mass spectroscopy
04/2008: pages 798 - 805; , ISBN: 9783527619917
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A L Cavalieri,
N Müller,
Th Uphues,
V S Yakovlev,
A Baltuska,
B Horvath,
B Schmidt,
L Blümel,
R Holzwarth,
S Hendel,
M Drescher, U Kleineberg,
P M Echenique,
R Kienberger,
F Krausz,
U Heinzmann
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ABSTRACT: Comprehensive knowledge of the dynamic behaviour of electrons in condensed-matter systems is pertinent to the development of many modern technologies, such as semiconductor and molecular electronics, optoelectronics, information processing and photovoltaics. Yet it remains challenging to probe electronic processes, many of which take place in the attosecond (1 as = 10(-18) s) regime. In contrast, atomic motion occurs on the femtosecond (1 fs = 10(-15) s) timescale and has been mapped in solids in real time using femtosecond X-ray sources. Here we extend the attosecond techniques previously used to study isolated atoms in the gas phase to observe electron motion in condensed-matter systems and on surfaces in real time. We demonstrate our ability to obtain direct time-domain access to charge dynamics with attosecond resolution by probing photoelectron emission from single-crystal tungsten. Our data reveal a delay of approximately 100 attoseconds between the emission of photoelectrons that originate from localized core states of the metal, and those that are freed from delocalized conduction-band states. These results illustrate that attosecond metrology constitutes a powerful tool for exploring not only gas-phase systems, but also fundamental electronic processes occurring on the attosecond timescale in condensed-matter systems and on surfaces.
Nature 11/2007; 449(7165):1029-32. · 36.28 Impact Factor
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ABSTRACT: Electrons emit light, carry electric current, and bind atoms together to form molecules. Insight into and control of their atomic-scale motion are the key to understanding the functioning of biological systems, developing efficient sources of x-ray light, and speeding up electronics. Capturing and steering this electron motion require attosecond resolution and control, respectively (1 attosecond = 10(-18) seconds). A recent revolution in technology has afforded these capabilities: Controlled light waves can steer electrons inside and around atoms, marking the birth of lightwave electronics. Isolated attosecond pulses, well reproduced and fully characterized, demonstrate the power of the new technology. Controlled few-cycle light waves and synchronized attosecond pulses constitute its key tools. We review the current state of lightwave electronics and highlight some future directions.
Science 09/2007; 317(5839):769-75. · 31.20 Impact Factor
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M Uiberacker,
Th Uphues,
M Schultze,
A J Verhoef,
V Yakovlev,
M F Kling,
J Rauschenberger,
N M Kabachnik,
H Schröder,
M Lezius,
K L Kompa,
H-G Muller,
M J J Vrakking,
S Hendel, U Kleineberg,
U Heinzmann,
M Drescher,
F Krausz
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ABSTRACT: Atoms exposed to intense light lose one or more electrons and become ions. In strong fields, the process is predicted to occur via tunnelling through the binding potential that is suppressed by the light field near the peaks of its oscillations. Here we report the real-time observation of this most elementary step in strong-field interactions: light-induced electron tunnelling. The process is found to deplete atomic bound states in sharp steps lasting several hundred attoseconds. This suggests a new technique, attosecond tunnelling, for probing short-lived, transient states of atoms or molecules with high temporal resolution. The utility of attosecond tunnelling is demonstrated by capturing multi-electron excitation (shake-up) and relaxation (cascaded Auger decay) processes with subfemtosecond resolution.
Nature 05/2007; 446(7136):627-32. · 36.28 Impact Factor
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ABSTRACT: Single 170-as extreme ultraviolet (XUV) pulses delivering more than 10 6 photons/pulse at ∼100 eV at a repetition rate of 3 kHz are produced by ionizing neon with waveform-controlled sub-5 fs near-infrared (NIR) laser pulses and spectrally filtering the emerging near-cutoff high-harmonic continuum with a broadband, chirped multilayer molybdenum–silicon (Mo/Si) mirror.
New Journal of Physics New Journal of Physics. 01/2007; 9(9).
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U. Kleineberg,
W. Hachmann,
U. Heinzmann,
S. Hendel,
N. Kabachnik,
F. Krausz,
U. Neuhäusler,
M. Uiberacker,
Th. Uphues,
A. Wonisch,
V. Yakovlev
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ABSTRACT: Aperiodic XUV multilayer coatings with broad spectral bandwidth and flat dispersion characteristics have been developed and
fabricated as reflecting and spectrally filtering optical elements for attosecond XUV pulses. Based on a genetic computational
optimization algorithm aperiodic Mo/Si multilayer structures exhibiting up to 40 eV spectral bandwidth and pulse responses
down to about 100 attoseconds at 80 eV center photon energy could be simulated. An experimental multilayer design exhibiting
about 15 eV spectral bandwidth at 93 eV photon energy was realized and tested in an attosecond XUV pump – IR probe photoionization
experiment (attosecond streak camera) utilizing single attosecond pulses from a High Harmonic Generation source. The results
display the enhanced spectral bandwidth filtered by the aperiodic mirror which holds the potential for the extraction of single
XUV pulses shorter than 200 attoseconds.
12/2006: pages 409-415;
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ABSTRACT: Chirped Mo/Si multilayer coatings have been designed, fabricated, and characterized for use in extreme-ultraviolet attosecond experiments. By numerically simulating the reflection of the attosecond pulse from a multilayer mirror during the optimization procedure based on a genetic algorithm, we obtain optimized layer designs. We show that normal incidence chirped multilayer mirrors capable of reflecting pulses of approximately 100 attoseconds (as) duration can be designed by enhancing the reflectivity bandwidth and optimizing the phase-shift behavior. The chirped multilayer coatings have been fabricated by electron-beam evaporation in an ultrahigh vacuum in combination with ion-beam polishing of the interfaces and in situ reflectivity measurement for layer thickness control. To analyze the aperiodic layer structure by hard-x-ray reflectometry, we have developed an automatic fitting procedure that allows us to determine the individual layer thicknesses with an error of less than 0.05 nm. The fabricated chirped mirror may be used for production of 150-160 as pulses.
Applied Optics 07/2006; 45(17):4147-56. · 1.41 Impact Factor
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U. Neuhausler,
A. Oelsner,
J. Slieh,
M. Brzeska,
A. Wonisch,
T. Westerwalbesloh,
H. Bruckl,
M. Schicketanz,
N. Weber,
M. Escher,
M. Merkel,
G. Schonhense, U. Kleineberg,
U. Heinzmann
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ABSTRACT: We report on the development and first experimental results of a “at wavelength” full-field imaging technique for defect inspection of multilayer mask blanks for extreme ultraviolet (EUV) lithography. According to the International Semiconductor Roadmap by Sematech, less than 5×10<sup>-3</sup> defects per cm <sup>2</sup> should be present on such multilayer mask blank to enable mass production of microelectronics using EUV lithography, thus fast high-resolution methods for mask defect inspection and localization are needed. Our approach uses a photoemission electron microscope in a normal incidence illumination mode at 13 nm to image the photoelectron emission induced by the EUV wave field on the multilayer mask blank surface. We show that by these means, buried defects in the multilayer stack can be probed down to a lateral size of 50 nm.
Applied Physics Letters 02/2006; · 3.84 Impact Factor
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ABSTRACT: Coherent soft X-ray sources open the way to new capabilities in high-resolution imaging, site- and element-specific spectroscopy and biomicroscopy. In this paper we demonstrate imaging with a table-top soft X-ray microscope. By combining a laser driven high-harmonic light source, optimized for having the maximum brightness at around 100 eV, a pair of multilayer mirrors to select a narrow spectral band and acting simultaneously as a condenser and a Fresnel zone plate as microscope objective, we were able to resolve 200 nm structures of a diatom sample. Further, the pulsed nature of our X-ray source offers the possibility of time-resolved spectromicroscopy with a temporal resolution in the order of a few femtoseconds.
Ultramicroscopy 02/2005; 102(2):93-100. · 2.47 Impact Factor
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ABSTRACT: The growth structure of DMPC lipid layers on hydrophobic and hydrophilic alkylsilane-based self-assembled monolayers adsorbed on silicon has been investigated by means of X-ray reflectometry and atomic force microscopy. Hydrophilic modification of hydrophobically terminated ODS-SAMs has been achieved by dose-controlled irradiation with DUV light. While island formation of small DMPC bilayer islands is observed on hydrophobic SAM surfaces, closed layers of DMPC monolayers are formed on hydrophilic SAM surfaces. Furthermore, DMPC adsorption on chemically micropatterned substrates with alternating hydrophobic/hydrophilic surface properties has been studied by imaging ellipsometry and photoemission microscopy. Indication for at least partial bridging of hydrophobic areas by an adsorbed DMPC monolayer has been found.
Journal of Biotechnology 09/2004; 112(1-2):115-25. · 3.05 Impact Factor
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E Goulielmakis,
M Uiberacker,
R Kienberger,
A Baltuska,
V Yakovlev,
A Scrinzi,
Th Westerwalbesloh, U Kleineberg,
U Heinzmann,
M Drescher,
F Krausz
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ABSTRACT: The electromagnetic field of visible light performs approximately 10(15) oscillations per second. Although many instruments are sensitive to the amplitude and frequency (or wavelength) of these oscillations, they cannot access the light field itself. We directly observed how the field built up and disappeared in a short, few-cycle pulse of visible laser light by probing the variation of the field strength with a 250-attosecond electron burst. Our apparatus allows complete characterization of few-cycle waves of visible, ultraviolet, and/or infrared light, thereby providing the possibility for controlled and reproducible synthesis of ultrabroadband light waveforms.
Science 09/2004; 305(5688):1267-9. · 31.20 Impact Factor
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R Kienberger,
E Goulielmakis,
M Uiberacker,
A Baltuska,
V Yakovlev,
F Bammer,
A Scrinzi,
Th Westerwalbesloh, U Kleineberg,
U Heinzmann,
M Drescher,
F Krausz
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ABSTRACT: In Bohr's model of the hydrogen atom, the electron takes about 150 attoseconds (1 as = 10(-18) s) to orbit around the proton, defining the characteristic timescale for dynamics in the electronic shell of atoms. Recording atomic transients in real time requires excitation and probing on this scale. The recent observation of single sub-femtosecond (1 fs = 10(-15) s) extreme ultraviolet (XUV) light pulses has stimulated the extension of techniques of femtochemistry into the attosecond regime. Here we demonstrate the generation and measurement of single 250-attosecond XUV pulses. We use these pulses to excite atoms, which in turn emit electrons. An intense, waveform-controlled, few cycle laser pulse obtains 'tomographic images' of the time-momentum distribution of the ejected electrons. Tomographic images of primary (photo)electrons yield accurate information of the duration and frequency sweep of the excitation pulse, whereas the same measurements on secondary (Auger) electrons will provide insight into the relaxation dynamics of the electronic shell following excitation. With the current approximately 750-nm laser probe and approximately 100-eV excitation, our transient recorder is capable of resolving atomic electron dynamics within the Bohr orbit time.
Nature 03/2004; 427(6977):817-21. · 36.28 Impact Factor
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ABSTRACT: We present a method of deriving single layer thickness fluctuations of Mo/Si EUV multilayers from cross-sectional high-resolution transmission electron microscopy micrographs. The obtained thickness values for each layer are used in a layer model to calculate the grazing-incidence X-ray reflectivity (GIXRR) and the corresponding at-wavelength-reflectivity curves. Comparison with XRR measurements shows the strong effect of thickness fluctuations on the intensity of the secondary Kiessig fringes and the main Bragg maxima. This model results in substantially better reflectivity simulations than the standard periodic four-layer model or the assumption of statistically distributed (random) thickness errors. Results for reflectivity curves at 13-nm wavelength are discussed in terms of peak reflectivity, peak shift and further changes in the shape of the reflectivity curve.
Applied Physics A 09/2003; 77(5):607-611. · 1.63 Impact Factor
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ABSTRACT: We report on interferometry using a two-zone-plate common-path interferometer operating at a wavelength of 13nm. The interferometer was set up with a laser-driven high-harmonic source emitting radiation with the high degree of spatial and temporal coherence necessary for interferometry. The interferometer is suited for investigations of the coherence properties of the light source employed, as well as for simultaneous measurements of the real and imaginary part of the complex index of refraction in the 100eV regime. This is demonstrated in a proof of principle experiment with a piece of Zr-foil as the phase-shifting and absorbing sample.
Applied Physics B 06/2003; 76(8):885-889. · 2.19 Impact Factor
