Search results for "Atom and Molecular Physics and Optics"
showing 10 items of 13 documents
Beating Darwin-Bragg losses in lab-based ultrafast x-ray experiments
2017
The use of low temperature thermal detectors for avoiding Darwin-Bragg losses in lab-based ultrafast experiments has begun. An outline of the background of this new development is offered, showing the relevant history and initiative taken by this work. (C) 2017 Author(s). Funding Agencies|Knut and Alice Wallenberg Foundation; ERC [226136]; Finnish Funding Agency for Technology and Innovation TEKES; Academy of Finland [260880]; NIST Innovations in Measurement Science program; DOE Office of Basic Energy Sciences
Tracking Ca2+ ATPase intermediates in real time by x-ray solution scattering
2020
Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) transporters regulate calcium signaling by active calcium ion reuptake to internal stores. Structural transitions associated with transport have been characterized by x-ray crystallography, but critical intermediates involved in the accessibility switch across the membrane are missing. We combined time-resolved x-ray solution scattering (TR-XSS) experiments and molecular dynamics (MD) simulations for real-time tracking of concerted SERCA reaction cycle dynamics in the native membrane. The equilibrium [Ca2] E1 state before laser activation differed in the domain arrangement compared with crystal structures, and following laser-induced release o…
Hot-Carrier Generation in Plasmonic Nanoparticles: The Importance of Atomic Structure
2020
Metal nanoparticles are attractive for plasmon-enhanced generation of hot carriers, which may be harnessed in photochemical reactions. In this work, we analyze the coherent femtosecond dynamics of photon absorption, plasmon formation, and subsequent hot-carrier generation through plasmon dephasing using first-principles simulations. We predict the energetic and spatial hot-carrier distributions in small metal nanoparticles and show that the distribution of hot electrons is very sensitive to the local structure. Our results show that surface sites exhibit enhanced hot-electron generation in comparison to the bulk of the nanoparticle. While the details of the distribution depend on particle s…
Diagnostics for studies of novel laser ion acceleration mechanisms.
2014
Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel accelera…
Ultrastrong Coupling of a Single Molecule to a Plasmonic Nanocavity: A First-Principles Study
2022
| openaire: EC/H2020/838996/EU//RealNanoPlasmon Funding Information: We acknowledge financial support from the Swedish Research Council (VR Miljö, Grant No: 2016-06059), the Knut and Alice Wallenberg Foundation (Grant No: 2019.0140), the Polish National Science Center (projects 2019/34/E/ST3/00359 and 2019/35/B/ST5/02477). T.P.R. acknowledges support from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 838996 and support from the Academy of Finland under the Grant No. 332429. T.J.A. acknowledges support from the Project HPC-EUROPA3 (INFRAIA-2016-1-730897), with the support of the EC Research Innovation Action under the H…
Attosecond control of dissociative ionization of O2molecules
2011
We demonstrate that dissociative ionization of O(2) can be controlled by the relative delay between an attosecond pulse train (APT) and a copropagating infrared (IR) field. Our experiments reveal a dependence of both the branching ratios between a range of electronic states and the fragment angular distributions on the extreme ultraviolet (XUV) to IR time delay. The observations go beyond adiabatic propagation of dissociative wave packets on IR-induced quasistatic potential energy curves and are understood in terms of an IR-induced coupling between electronic states in the molecular ion.
Switching Dynamics of Dark Solitons in Kerr Microresonators
2019
Dissipative Kerr solitons (DKS) are localized structures in optical resonators that arise from a double balance between dispersion and Kerr effect, and linear loss and parametric gain [1]. The periodic nature of DKS corresponds to frequency combs. DKS can be generated in high-Q microresonators for diverse applications, from coherent communications to precision frequency synthesis [1]. Most studies of DKS have focused on microresonator cavities operating in the anomalous dispersion regime, where the waveforms correspond to bright soliton pulses. Coherent microresonator combs can also be formed in the normal dispersion regime [2]. The time-domain waveform corresponds to a localized dark-pulse…
Plasmon excitations in chemically heterogeneous nanoarrays
2020
| openaire: EC/H2020/838996/EU//RealNanoPlasmon The capability of collective excitations, such as localized surface plasmon resonances, to produce a versatile spectrum of optical phenomena is governed by the interactions within the collective and single-particle responses in the finite system. In many practical instances, plasmonic metallic nanoparticles and arrays are either topologically or chemically heterogeneous, which affects both the constituent transitions and their interactions. Here, the formation of collective excitations in weakly Cu- and Pd-doped Au nanoarrays is described using time-dependent density functional theory. The additional impurity-induced modes in the optical respo…
Hot-cavity spectroscopy of dark pulse Kerr combs in microresonators
2019
Kerr frequency combs are generated through cascaded four-wave mixing in high-Q microresonators [1]. These devices are pumped with a continuous-wave laser and modulational instability (MI) is responsible for the growth of the initial comb lines. Since it is easier to satisfy the MI phase matching condition in the anomalous dispersion regime, most studies on Kerr combs have focused on anomalous dispersion microresonators. However, coherent microresonator combs can also take place in the normal dispersion regime. In these combs, phase matching is attained with the aid of the mode coupling between transverse modes of the microresonator [2]. One particularly interesting comb state that operates …
Triply resonant coherent four-wave mixing in silicon nitride microresonators
2015
The generation of multiple tones using four-wave mixing (FWM) has been exploited for many applications, ranging from wavelength conversion to frequency comb generation. FWM is a coherent process, meaning that its dynamics strongly depends on the relative phase among the waves involved. The coherent nature of FWM has been exploited for phase-sensitive processing in different waveguide structures, but it has never been studied in integrated microresonators. Waveguides arranged in a resonant way allow for an effective increase in the wavelength conversion efficiency (at the expense of a reduction in the operational bandwidth). In this letter, we show that phase shaping of a three-wave pump pro…