L. Gallmann
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View article: Phonon-mode-specific modulation of electronic states in molybdenum dioxide
Phonon-mode-specific modulation of electronic states in molybdenum dioxide Open
Near-infrared pump and extreme ultraviolet probe transient absorption spectroscopy is employed to unravel the phonon-mode-specific modifications of electronic states near the Fermi energy in molybdenum dioxide. We observe distinct fingerpr…
View article: Hot-electron-induced substrate response in transient absorption spectroscopy of tantalum
Hot-electron-induced substrate response in transient absorption spectroscopy of tantalum Open
We demonstrate that for extreme ultraviolet (XUV) transient absorption spectroscopy measurements of thin-film metals, the substrate can significantly contribute to the observed change in absorption even if it is transparent to the pump pul…
View article: Ultrafast Transition from State-Blocking Dynamics to Electron Localization in Transition Metal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>-Tungsten
Ultrafast Transition from State-Blocking Dynamics to Electron Localization in Transition Metal -Tungsten Open
We describe an ultrafast transition of the electronic response of optically excited transition metal β-tungsten with few-femtosecond time resolution. The response moves from a regime where state filling of the excited carrier population ar…
View article: Ultrafast electron localization and screening in a transition metal dichalcogenide
Ultrafast electron localization and screening in a transition metal dichalcogenide Open
The coupling of light to electrical charge carriers in semiconductors is the foundation of many technological applications. Attosecond transient absorption spectroscopy measures simultaneously how excited electrons and the vacancies they l…
View article: Breakdown of the single-collision condition for soft x-ray high harmonic generation in noble gases
Breakdown of the single-collision condition for soft x-ray high harmonic generation in noble gases Open
High harmonic generation (HHG) in atomic gases is generally assumed to originate from photoelectrons that are not perturbed by neighboring particles. In this paper, we study theoretically and experimentally the regime where this approximat…
View article: Ultrafast electron localization and screening in a transition metal dichalcogenide
Ultrafast electron localization and screening in a transition metal dichalcogenide Open
The coupling of light to electrical charge carriers in semiconductors is the foundation of many technological applications. Attosecond transient absorption spectroscopy measures simultaneously how excited electrons and the vacancies they l…
View article: Few-Femtosecond Dynamics of Free-Free Opacity in Optically Heated Metals
Few-Femtosecond Dynamics of Free-Free Opacity in Optically Heated Metals Open
Interaction of light with an excited free-electron gas is a fundamental process spanning a large variety of fields in physics. The advent of femtosecond laser pulses and extreme-ultraviolet sources allowed one to put theoretical models to …
View article: Sub-Cycle Phonon Dynamics Induced by Ultrafast Electron-Phonon Relaxations in 2D Carbide Ti3C2Tx (MXene)
Sub-Cycle Phonon Dynamics Induced by Ultrafast Electron-Phonon Relaxations in 2D Carbide Ti3C2Tx (MXene) Open
Attosecond transient absorption spectroscopy in two-dimensional functionalized transition metal carbide unveils ultrafast element, site, and carrier-specific electron-phonon relaxations on the few-femtosecond timescale and provides new ins…
View article: Water-window high harmonic generation with 0.8-µm and 2.2-µm OPCPAs at 100 kHz
Water-window high harmonic generation with 0.8-µm and 2.2-µm OPCPAs at 100 kHz Open
We compare the generation of high-order harmonics in the water window (283-543 eV) with 0.8-µm and 2.2-µm few-cycle lasers at a pulse repetition rate of 100 kHz. Using conventional phase matching with the 2.2-µm driver and what we attribut…
View article: Figure 6: 0.8-µm driven HHG at high photon energies
Figure 6: 0.8-µm driven HHG at high photon energies Open
(a-b) Pressure scans in helium and neon for HHG with the 0.8-µm driver in a 1-mm long drilled gas cell at a peak intensity estimated to 2.6×10^(16) W/cm^2. (c) Raw spectrum without amplitude correction for HHG in helium at 380 mbar backing…
View article: Figure 7: Experimental comparison between conventional phase matching with a 2.2-µm driver and unconventional phase matching with a 0.8-µm driver
Figure 7: Experimental comparison between conventional phase matching with a 2.2-µm driver and unconventional phase matching with a 0.8-µm driver Open
Experimental HHG spectra with a 0.8 µm and a 2.2 µm driver in helium and neon. The different generation parameters are summarized in Table 1. All spectra are recorded with the same grating (2400 g/mm), except the 2×10^(15) W/cm^2 case, rec…
View article: Figure 8: Effect of the peak intensity and the presence of pre-pulses on the HHG efficiency at high photon energies with a 0.8-µm driver
Figure 8: Effect of the peak intensity and the presence of pre-pulses on the HHG efficiency at high photon energies with a 0.8-µm driver Open
(a) Measurement of the SXR spectrum as a function of the peak intensity in 390 mbar of helium in a 1-mm long drilled gas cell. The power is adjusted from 4 to 20 W by steps of 1 W with an iris placed before the off-axis parabola. (b) Measu…
View article: High-power few-cycle near-infrared OPCPA for soft X-ray generation at 100 kHz
High-power few-cycle near-infrared OPCPA for soft X-ray generation at 100 kHz Open
We present a near-infrared optical parametric chirped-pulse amplifier (OPCPA) and soft X-ray (SXR) high-harmonic generation system. The OPCPA produces few-cycle pulses at a center wavelength of 800 nm and operates at a high repetition rate…
View article: Attosecond timing of the dynamical Franz–Keldysh effect
Attosecond timing of the dynamical Franz–Keldysh effect Open
To what extent do intra- or inter-band transitions dominate the optical response of dielectrics when pumped by a few-cycle near-infrared transient electric field? In order to find an answer to this question we investigate the dynamical Fra…
View article: Phase stabilization of an attosecond beamline combining two IR colors
Phase stabilization of an attosecond beamline combining two IR colors Open
We present a phase-stabilized attosecond pump-probe beamline involving two separate infrared wavelengths for high-harmonic generation (HHG) and pump or probe. The output of a Ti:sapphire laser is partly used to generate attosecond pulses v…
View article: Reduction of laser-intensity-correlated noise in high-harmonic generation
Reduction of laser-intensity-correlated noise in high-harmonic generation Open
We present a scheme for correcting the spectral fluctuations of high-harmonic radiation. We show that the fluctuations of the extreme-ultraviolet (XUV) spectral power density can be predicted solely by monitoring the generating laser pulse…
View article: Ultrafast nuclear dynamics of the acetylene cation C<sub>2</sub>H<sub>2</sub><sup>+</sup> and its impact on the infrared probe pulse induced C–H bond breaking efficiency
Ultrafast nuclear dynamics of the acetylene cation C<sub>2</sub>H<sub>2</sub><sup>+</sup> and its impact on the infrared probe pulse induced C–H bond breaking efficiency Open
We track the few-femtosecond excited-state dynamics of the acetylene cation through modulations of the C2H+ photofragment yield.
View article: High-power OPCPA generating 17 cycle pulses at 25 µm
High-power OPCPA generating 17 cycle pulses at 25 µm Open
We present a high-power mid-infrared (mid-IR) optical parametric chirped-pulse amplifier (OPCPA) generating 14.4 fs pulses centered at 2.5 µm with an average power of 12.6 W and a repetition rate of 100 kHz. The short pulses are obtained w…
View article: Role of intraband transitions in photocarrier generation
Role of intraband transitions in photocarrier generation Open
We theoretically investigate the role of intra-band transitions in laser-induced carrier-generation for different photon energy regimes: (i) strongly off-resonant, (ii) multi-photon resonant, and (iii) resonant conditions. Based on the ana…
View article: Interplay between Coulomb-focusing and non-dipole effects in strong-field ionization with elliptical polarization
Interplay between Coulomb-focusing and non-dipole effects in strong-field ionization with elliptical polarization Open
We study strong-field ionization and rescattering beyond the long-wavelength limit of the dipole approximation with elliptically polarized mid-IR laser pulses. Full three-dimensional photoelectron momentum distributions (PMDs) measured wit…
View article: Decoupling phase-matching bandwidth and interaction geometry using non-collinear quasi-phase-matching gratings
Decoupling phase-matching bandwidth and interaction geometry using non-collinear quasi-phase-matching gratings Open
In optical parametric amplification (OPA) of broadband pulses, a non-collinear angle between the interacting waves is typically introduced in order to achieve broadband phase-matching. Consequently, bandwidth and beam geometry are closely …
View article: Probing the ionization wave packet and recollision dynamics with an elliptically polarized strong laser field in the nondipole regime
Probing the ionization wave packet and recollision dynamics with an elliptically polarized strong laser field in the nondipole regime Open
ISSN:1094-1622
View article: Effective mass effect in attosecond electron transport
Effective mass effect in attosecond electron transport Open
The electronic band structure governs the electron dynamics in solids. It defines a group velocity and an effective mass of the electronic wave packet. Recent experimental and theoretical studies suggest that an electron acquires the effec…
View article: Photoemission and photoionization time delays and rates
Photoemission and photoionization time delays and rates Open
Ionization and, in particular, ionization through the interaction with light play an important role in fundamental processes in physics, chemistry, and biology. In recent years, we have seen tremendous advances in our ability to measure th…
View article: Strong field transient manipulation of electronic states and bands
Strong field transient manipulation of electronic states and bands Open
In the present review, laser fields are so strong that they become part of the electronic potential, and sometimes even dominate the Coulomb contribution. This manipulation of atomic potentials and of the associated states and bands finds …
View article: Comparison of attosecond streaking and RABBITT
Comparison of attosecond streaking and RABBITT Open
Recent progress in the generation of ultra-short laser pulses has enabled the measurement of photoionization time delays with attosecond precision. For single photoemission time delays the most common techniques are based on attosecond str…
View article: Interplay between Coulomb-focusing and non-dipole effects in strong-field ionization with elliptical polarization
Interplay between Coulomb-focusing and non-dipole effects in strong-field ionization with elliptical polarization Open
Strong-field ionization and rescattering beyond the long-wavelength limit of the dipole approximation is studied with elliptically polarized mid-IR pulses. We have measured the full three-dimensional photoelectron momentum distributions (3…
View article: Gouy phase shift for annular beam profiles in attosecond experiments
Gouy phase shift for annular beam profiles in attosecond experiments Open
Attosecond pump-probe measurements are typically performed by combining attosecond pulses with more intense femtosecond, phase-locked infrared (IR) pulses because of the low average photon flux of attosecond light sources based on high-har…