Filters

202222

More filters

2022 - 202322
Reset filters

Settings

End date: 2022 × Start date: 2022 × DDC: 530 × Type: Article × WGL Institute: MBI ×

Search Results

Now showing 1 - 10 of 22
  • Thumbnail Image
    Item
    Short-Range Cooperative Slow-down of Water Solvation Dynamics Around SO42--Mg2+ Ion Pairs
    (Washington, DC : American Chemical Society, 2022) Kundu, Achintya; Mamatkulov, Shavkat I.; Brünig, Florian N.; Bonthuis, Douwe Jan; Netz, Roland R.; Elsaesser, Thomas; Fingerhut, Benjamin P.
    The presence of ions affects the structure and dynamics of water on a multitude of length and time scales. In this context, pairs of Mg2+ and SO42- ions in water constitute a prototypical system for which conflicting pictures of hydration geometries and dynamics have been reported. Key issues are the molecular pair and solvation shell geometries, the spatial range of electric interactions, and their impact on solvation dynamics. Here, we introduce asymmetric SO42- stretching vibrations as new and most specific local probes of solvation dynamics that allow to access ion hydration dynamics at the dilute concentration (0.2 M) of a native electrolyte environment. Highly sensitive heterodyne 2D-IR spectroscopy in the fingerprint region of the SO42- ions around 1100 cm-1 reveals a specific slow-down of solvation dynamics for hydrated MgSO4 and for Na2SO4 in the presence of Mg2+ ions, which manifests as a retardation of spectral diffusion compared to aqueous Na2SO4 solutions in the absence of Mg2+ ions. Extensive molecular dynamics and density functional theory QM/MM simulations provide a microscopic view of the observed ultrafast dephasing and hydration dynamics. They suggest a molecular picture where the slow-down of hydration dynamics arises from the structural peculiarities of solvent-shared SO42--Mg2+ ion pairs.
  • Thumbnail Image
    Item
    Nanostructured In3SbTe2 antennas enable switching from sharp dielectric to broad plasmonic resonances
    (Berlin : de Gruyter, 2022) Heßler, Andreas; Wahl, Sophia; Kristensen, Philip Trøst; Wuttig, Matthias; Busch, Kurt; Taubner, Thomas
    Phase-change materials (PCMs) allow for non-volatile resonance tuning of nanophotonic components. Upon switching, they offer a large dielectric contrast between their amorphous and crystalline phases. The recently introduced “plasmonic PCM” In3SbTe2 (IST) additionally features in its crystalline phase a sign change of its permittivity over a broad infrared spectral range. While optical resonance switching in unpatterned IST thin films has been investigated before, nanostructured IST antennas have not been studied, yet. Here, we present numerical and experimental investigations of nanostructured IST rod and disk antennas. By crystallizing the IST with microsecond laser pulses, we switched individual antennas from narrow dielectric to broad plasmonic resonances. For the rod antennas, we demonstrated a resonance shift of up to 1.2 µm (twice the resonance width), allowing on/off switching of plasmonic resonances with a contrast ratio of 2.7. With the disk antennas, we realized an increase of the resonance width by more than 800% from 0.24 µm to 1.98 µm while keeping the resonance wavelength constant. Further, we demonstrated intermediate switching states by tuning the crystallization depth within the resonators. Our work empowers future design concepts for nanophotonic applications like active spectral filters, tunable absorbers, and switchable flat optics.
  • Thumbnail Image
    Item
    A general approach for all-visible-light switching of diarylethenes through triplet sensitization using semiconducting nanocrystals
    (London [u.a.] : RSC, 2022) Hou, Lili; Larsson, Wera; Hecht, Stefan; Andréasson, Joakim; Albinsson, Bo
    Coupling semiconducting nanocrystals (NCs) with organic molecules provides an efficient route to generate and transfer triplet excitons. These excitons can be used to power photochemical transformations such as photoisomerization reactions using low energy radiation. Thus, it is desirable to develop a general approach that can efficiently be used to control photoswitches using all-visible-light aiming at future applications in life- and materials sciences. Here, we demonstrate a simple ‘cocktail’ strategy that can achieve all-visible-light switchable diarylethenes (DAEs) through triplet energy transfer from the hybrid of CdS NCs and phenanthrene-3-carboxylic acid, with high photoisomerization efficiency and improved fatigue resistance. The size-tunable excitation energies of CdS NCs make it possible to precisely match the clear spectral window of the relevant DAE photoswitch. We demonstrate reversible all-visible-light photoisomerization of a series of DAE derivatives both in the liquid and solid state, even in the presence of oxygen. Our general strategy is promising for fabrication of all-visible-light activated optoelectronic devices as well as memories, and should in principle be adaptable to photopharmacology.
  • Thumbnail Image
    Item
    High power, high repetition rate laser-based sources for attosecond science
    (Bristol : IOP Publishing, 2022) Furch, F.J.; Witting, T.; Osolodkov, M.; Schell, F.; Schulz, C.P.; Vrakking, M.J.
    Within the last two decades attosecond science has been established as a novel research field providing insights into the ultrafast electron dynamics that follows a photoexcitation or photoionization process. Enabled by technological advances in ultrafast laser amplifiers, attosecond science has been in turn, a powerful engine driving the development of novel sources of intense ultrafast laser pulses. This article focuses on the development of high repetition rate laser-based sources delivering high energy pulses with a duration of only a few optical cycles, for applications in attosecond science. In particular, a high power, high repetition rate optical parametric chirped pulse amplification system is described, which was developed to drive an attosecond pump-probe beamline targeting photoionization experiments with electron-ion coincidence detection at high acquisition rates.
  • Thumbnail Image
    Item
    General Time-Dependent Configuration-Interaction Singles II: The Atomic Case
    (Woodbury, NY : Inst., 2022-10-10) Carlström, Stefanos; Bertolino, Mattias; Dahlström, Jan Marcus; Patchkovskii, Serguei
    We present a specialization of the grid-based implementation of the time-dependent configuration-interaction singles described in the preceding paper [S. Carlström et al., preceding paper, Phys. Rev. A 106, 043104 (2022)]. to the case of spherical symmetry. We describe the intricate time propagator in detail and conclude with a few example calculations. Among these, of note are high-resolution photoelectron spectra in the vicinity of the Fano resonances in photoionization of neon and spin-polarized photoelectrons from xenon, in agreement with recent experiments.
  • Thumbnail Image
    Item
    General Time-Dependent Configuration-Interaction Singles I: The Molecular Case
    (Woodbury, NY : Inst., 2022-10-10) Carlström, Stefanos; Spanner, Michael; Patchkovskii, Serguei
    We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in our treatment of this method, we present example calculations of strong-field ionization of He, LiH, H2O, and C2H4 that demonstrate the utility of our implementation. The following paper [S. Carlström et al., following paper, Phys. Rev. A 106, 042806 (2022)] specializes to the case of spherical symmetry, which is applied to various atoms.
  • Thumbnail Image
    Item
    Reference shape effects on Fourier transform holography
    (Washington, DC : Soc., 2022) Malm, Erik; Pfau, Bastian; Schneider, Michael; Günther, Christian M.; Hessing, Piet; Büttner, Felix; Mikkelsen, Anders; Eisebitt, Stefan
    Soft-x-ray holography which utilizes an optics mask fabricated in direct contact with the sample, is a widely applied x-ray microscopy method, in particular, for investigating magnetic samples. The optics mask splits the x-ray beam into a reference wave and a wave to illuminate the sample. The reconstruction quality in such a Fourier-transform holography experiment depends primarily on the characteristics of the reference wave, typically emerging from a small, high-aspect-ratio pinhole in the mask. In this paper, we study two commonly used reference geometries and investigate how their 3D structure affects the reconstruction within an x-ray Fourier holography experiment. Insight into these effects is obtained by imaging the exit waves from reference pinholes via high-resolution coherent diffraction imaging combined with three-dimensional multislice simulations of the x-ray propagation through the reference pinhole. The results were used to simulate Fourier-transform holography experiments to determine the spatial resolution and precise location of the reconstruction plane for different reference geometries. Based on our findings, we discuss the properties of the reference pinholes with view on application in soft-x-ray holography experiments.
  • Thumbnail Image
    Item
    All-optical Stückelberg spectroscopy of strongly driven Rydberg states
    (College Park, MD : APS, 2022) Bengs, Ulrich; Patchkovskii, Serguei; Ivanov, Misha; Zhavoronkov, Nickolai
    The AC Stark shift of electronic levels is ubiquitous in the interaction of intense light fields with atoms and molecules. As the light intensity changes on the rising and falling edges of a femtosecond laser pulse, it shifts the Rydberg states in and out of multiphoton resonances with the ground state. The two resonant pathways for transient excitation arising at the leading and the trailing edges of the pulse generate Young's type interference, generally referred to as the Stückelberg oscillations. Here we report the observation of the Stückelberg oscillations in the intensity of the coherent free-induction decay following resonant multiphoton excitation. Moreover, combining the experimental results with accurate numerical simulations and a simple model, we use the Stückelberg oscillations to recover the population dynamics of strongly driven Rydberg states inside the laser pulse by all-optical measurements after the end of the pulse. We demonstrate the potential of this spectroscopy to characterize lifetimes of Rydberg states dressed by laser fields with strengths far exceeding the Coulomb field between the Rydberg electron and the core.
  • Thumbnail Image
    Item
    Coherent control of the photoinduced transition in a strongly correlated material
    (College Park, MD : APS, 2022) Molinero, Eduardo B.; Silva, Rui E. F.
    The use of intense tailored light fields is the perfect tool to achieve ultrafast control of electronic properties in quantum materials. Among them, Mott insulators are materials in which strong electron-electron interactions drive the material into an insulating phase. When shining a Mott insulator with a strong laser pulse, the electric field may induce the creation of doublon-hole pairs, triggering a photoinduced transition into a metallic state. In this paper, we take advantage of the threshold character of this photoinduced transition and we propose a setup that consists of a midinfrared laser pulse and a train of short pulses separated by a half period of the midinfrared with alternating phases. By varying the time delay between the two pulses and the internal carrier envelope phase of the short pulses, we achieve control of the phase transition, which leaves its fingerprint at its high harmonic spectrum.
  • Thumbnail Image
    Item
    The 2022 magneto-optics roadmap
    (Bristol : IOP Publ., 2022-09-28) Kimel, Alexey; Zvezdin, Anatoly; Sharma, Sangeeta; Shallcross, Samuel; de Sousa, Nuno; García-Martín, Antonio; Salvan, Georgeta; Hamrle, Jaroslav; Stejskal, Ondřej; McCord, Jeffrey; Tacchi, Silvia; Carlotti, Giovanni; Gambardella, Pietro; Salis, Gian; Münzenberg, Markus; Schultze, Martin; Temnov, Vasily; Bychkov, Igor V.; Kotov, Leonid N.; Maccaferri, Nicolò; Ignatyeva, Daria; Belotelov, Vladimir; Donnelly, Claire; Rodriguez, Aurelio Hierro; Matsuda, Iwao; Ruchon, Thierry; Fanciulli, Mauro; Sacchi, Maurizio; Du, Chunhui Rita; Wang, Hailong; Armitage, N. Peter; Schubert, Mathias; Darakchieva, Vanya; Liu, Bilu; Huang, Ziyang; Ding, Baofu; Berger, Andreas; Vavassori, Paolo
    Magneto-optical (MO) effects, viz. magnetically induced changes in light intensity or polarization upon reflection from or transmission through a magnetic sample, were discovered over a century and a half ago. Initially they played a crucially relevant role in unveiling the fundamentals of electromagnetism and quantum mechanics. A more broad-based relevance and wide-spread use of MO methods, however, remained quite limited until the 1960s due to a lack of suitable, reliable and easy-to-operate light sources. The advent of Laser technology and the availability of other novel light sources led to an enormous expansion of MO measurement techniques and applications that continues to this day (see section 1). The here-assembled roadmap article is intended to provide a meaningful survey over many of the most relevant recent developments, advances, and emerging research directions in a rather condensed form, so that readers can easily access a significant overview about this very dynamic research field. While light source technology and other experimental developments were crucial in the establishment of today's magneto-optics, progress also relies on an ever-increasing theoretical understanding of MO effects from a quantum mechanical perspective (see section 2), as well as using electromagnetic theory and modelling approaches (see section 3) to enable quantitatively reliable predictions for ever more complex materials, metamaterials, and device geometries. The latest advances in established MO methodologies and especially the utilization of the MO Kerr effect (MOKE) are presented in sections 4 (MOKE spectroscopy), 5 (higher order MOKE effects), 6 (MOKE microscopy), 8 (high sensitivity MOKE), 9 (generalized MO ellipsometry), and 20 (Cotton–Mouton effect in two-dimensional materials). In addition, MO effects are now being investigated and utilized in spectral ranges, to which they originally seemed completely foreign, as those of synchrotron radiation x-rays (see section 14 on three-dimensional magnetic characterization and section 16 on light beams carrying orbital angular momentum) and, very recently, the terahertz (THz) regime (see section 18 on THz MOKE and section 19 on THz ellipsometry for electron paramagnetic resonance detection). Magneto-optics also demonstrates its strength in a unique way when combined with femtosecond laser pulses (see section 10 on ultrafast MOKE and section 15 on magneto-optics using x-ray free electron lasers), facilitating the very active field of time-resolved MO spectroscopy that enables investigations of phenomena like spin relaxation of non-equilibrium photoexcited carriers, transient modifications of ferromagnetic order, and photo-induced dynamic phase transitions, to name a few. Recent progress in nanoscience and nanotechnology, which is intimately linked to the achieved impressive ability to reliably fabricate materials and functional structures at the nanoscale, now enables the exploitation of strongly enhanced MO effects induced by light–matter interaction at the nanoscale (see section 12 on magnetoplasmonics and section 13 on MO metasurfaces). MO effects are also at the very heart of powerful magnetic characterization techniques like Brillouin light scattering and time-resolved pump-probe measurements for the study of spin waves (see section 7), their interactions with acoustic waves (see section 11), and ultra-sensitive magnetic field sensing applications based on nitrogen-vacancy centres in diamond (see section 17). Despite our best attempt to represent the field of magneto-optics accurately and do justice to all its novel developments and its diversity, the research area is so extensive and active that there remains great latitude in deciding what to include in an article of this sort, which in turn means that some areas might not be adequately represented here. However, we feel that the 20 sections that form this 2022 magneto-optics roadmap article, each written by experts in the field and addressing a specific subject on only two pages, provide an accurate snapshot of where this research field stands today. Correspondingly, it should act as a valuable reference point and guideline for emerging research directions in modern magneto-optics, as well as illustrate the directions this research field might take in the foreseeable future.