bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effective modulation of the terahertz radiation force
Authors: Zhang X B , Qiao X , Zhang A X , Xue J K 
Published: June 2020

Synopsis
The radiation force of the terahertz field is realized and highly modulated by changing the spatial distribution of the THz field, which is controlled by the coupling effects of the laser field, external magnetic field, and self-generated plasma channel. Moreover, the stability of the terahertz radiation is also discussed.
Programmable plasma structure generated by the laser-plasma interaction
Authors: Zhang X B , Qiao X , Zhang A X , Xue J K 
Published: June 2020

Synopsis
The programmable plasma structure generated by the laser-plasma interaction is discussed theoretically. The multiple plasma density distribution patterns which includes single channel, double channel and slow-wave plasma structure is achieved by modulating the ponderomotive force controlled by the laser’s beam profile and pulse width.
Ammonia ices under low-energy electron irradiation - Towards quantitative desorption rates and effective cross sections
Authors: Sala L , Amiaud L , Dablemont C , Lafosse A 
Published: June 2020

Synopsis
Low-energy (< 20 eV) electron processing of NH3 multilayer films, systems of interest in astrochemistry, leads to significant NH3 desorption, fragmentation, and to a complex chemistry arising from recombination and secondary processes induced by reactive products. Quantitative desorption rates of neutral species and effective cross sections for selected processes were obtained by combining three surface-sensitive techniques: High Resolution Electron-Energy Loss Spectroscopy (HREELS), Temperature Programmed Desorption (TPD) and Electron Stimulated Desorption (ESD) of neutral species.
Resonant anionic states of organic molecules adsorbed on metal surfaces
Authors: Aguilar-Galindo F , Díaz-Tendero S , Borisov A G 
Published: June 2020

Synopsis
The interaction of organic molecules with metal surfaces induces drastic changes in the electronic structure of the adsorbate. In particular, properties such as the energy and the lifetime of anionic states are strongly modified. Decay into the metal continuum must be considered in the electron dynamics, since in many cases it dominates over the decay through the vacuum. We present a generalized methodology to study this kind of systems in order to obtain the energy of the states, as well as their lifetime and decay paths.
Many body phenomenon within multiple scattering approach in PEELS
Authors: Mandal A , Kochetov V , Dhankhar N , Sébilleaut D , Choubisa R 
Published: June 2020

Synopsis
Plasmon excitation within multiple scattering approach is being explored. The plasmon loss is described within the so-called quasi-boson approximation, originally proposed by Hedin and further extended by Fujikawa. We compare the different fluctuation potentials i.e. Plasmon-pole model, Bechstedt model and other available potentials based on beyond-RPA dielectric functions and use either the exact core state wave function or more accurate model than a simple delta function used previously for total energy loss in Aluminium targets.
Photoionization of endohedrals: complete semi-phenomenological approach
Authors: Amusia M Ya , Chernysheva L V 
Published: June 2020

Synopsis
We developed a semi-phenomenological approach that permits to calculate the photoionization cross section of an endohedral A@CN. We take, along with the static pseudopotential of atom A and fullerene CN also the static and dynamic polarization of A and CN by the incoming photons and outgoing electrons. The approach is general and applicable to any spherically-symmetric endohedrals. Concrete results are obtained for Ar@C60 and Xe@C60. We take into account the multi-electron correlations in the frame of the random phase approximation with exchange (RPAE).
Profile of energy-loss spectrum in collisions of ions with heteronuclear diatomic molecules
Authors: Nakamura M , Ichimura A 
Published: June 2020

Synopsis
Profile of energy-loss spectrum in collisions of low velocity ions with heteronuclear diatomic molecules is theoretically investigated. With changing mass asymmetry in a target diatomic molecule, energy-loss spectrum is calculated with the classical trajectory calculation. Rotational excitation plays an essential role for energy-loss. The shape of the spectrum is found to show a drastic variation with mass asymmetry.
Diffraction of 80 eV hydrogen through suspended graphene
Authors: Brand C , Susi T , Kotakoski J , Arndt M , Debiossac M , Aguillon F , Roncin P 
Published: June 2020

Synopsis
We have investigated theoretically the possibility to diffract hydrogen atoms through a suspended graphene single layer. Using quantum and semi classical approaches we evaluate the momentum and energy exchange to the electronic and vibrational system and estimate their influence on the coherence and spot size.
On the mechanisms of formation and decomposition of peptide bonds
Authors: Bolognesi P , Chiarinelli J , Richter R , Stockett M H , Indrajith S , Nicolafrancesco C , Eklund G , Zettergren H , Sa’adeh H , Domaracka A , Rousseau P , Avaldi L 
Published: June 2020

Synopsis
The electronic structure and the fragmentation dynamics of a series of isolated cyclic-dipeptides (cyclo-Ala-Ala; cyclo-Gly-Ala; cyclo-Gly-Gly) have been studied by mass spectrometry, photoemission and photoelectron-photoion coincidence spectroscopy.
Path integral molecular dynamics simulations for muoniated and hydrogenated thioacetone radicals
Authors: Okano S , Oba Y , Tachikawa M 
Published: June 2020

Synopsis
Theoretical understanding of hyperfine coupling constant (HFCC) is important to analyze muon spin rotation/relaxation/resonance (μSR) spectrum. We performed ab initio path integral molecular dynamics simula-tions to predict and analyze the reduced HFCCs of muoniated thioacetone radical (Mu-TACE) and hydrogenated thioacetone radical (H-TACE). Our predicted HFCC value of Mu in Mu-TACE was larger than that of H in H-TACE, because of the larger nuclear quantum effect of positive muon.
Vibrational and rotational cooling dynamics of the triatomic molecular ion N2O+ stored in RICE
Authors: Igosawa R , Hirota A , Yamaguchi T , Lindley M , Chartkunchand K , Nakano Y , Kuma S , Azuma T 
Published: June 2020

Synopsis
We studied radiative cooling dynamics of the triatomic molecular ion N2O+ stored in RICE. We observed the evolution of the populations at vibrational and rotational levels up to several 100 s by measuring neutral fragments from the laser-induced predissociation process. We found clear evidence of radiative cooling of the vibrational level populations with a time constant of several seconds. In contrast, absence of significant changes in the rotational levels revealed that the time scale of the rotational cooling is far longer, which is consistent to our simulation.
State-selected ion-molecule reactions with VUV synchrotron radiation : the O2
+ + C3H6 case
Authors: Thissen R , Romanzin C , Lemaire J , Thomas S , Alcaraz C 
Published: June 2020

Synopsis
O2
+ molecular ion is produced by photoionization close to threshold at SOLEIL, DESIRS beam line. By means of coincidence methods, ions are prepared in selected vibrational and electronic states (X, v=0,3,15 and a, v=3). Their reactivity with the propene in single collision regime is studied in the guided ion beam in-strument CERISES, adding ability to vary the collision energy. Absolute reaction cross section and branching ratio are recorded for the 5 most intense reactive channels, described as dissociative charge transfer. Contrasted effects of internal and collision energy are observed.
Radiative cooling dynamics of anthracene cations stored in DESIREE studied via the time evolution of 2-photon-absorption induced dissociation rate
Authors: Bernard J , Ji M C , Martin S , Wenzel G , Al-Mogeeth A , Stockett M H , Schmidt H T , Zettergren H , Joblin C 
Published: June 2020

Synopsis
Anthracene cations (C14H10
+) have been stored in the cryogenic (13 K) electrostatic storage ring DESIREE in Stockholm to study their radiative cooling dynamics on a long time scale up to 2 s. By monitoring the laser-induced delayed dissociation curves during the storage, the evolution of the dissociation rate was obtained. Its decrease as a function of time is closely related to the time evolution of the internal energy distribution of the stored anthracene cations and consequently to the energy loss due to radiative cooling, including both Poincaré and infrared fluorescences.
DAVIS: a direct algorithm for velocity-map imaging system
Authors: Harrison G R , Vaughan J C , Hidle B , Laurent G M 
Published: June 2020

Synopsis
Recently, we reported a direct (non-iterative) algorithm to reconstruct the three-dimensional momentum-space picture of any charged particles collected with a velocity-map imaging system from the two-dimensional projected image captured by a position-sensitive detector. The method consists of fitting the measured image with an analytical 2D projection of a model 3D velocity distribution defined by the physics of the light-matter interaction. In this work, we present a systematic comparison of the level of performance (accuracy and speed) of our method with others well-known techniques for inverting experimental images.
XUV+IR photoionization of argon atoms: selection of sideband orders
Authors: Picca R Della , Gramajo A A , López S , Arbó D G 
Published: June 2020

Abstract
We present a theoretical study of atomic ionization due to an XUV pulse in the presence of an infrared laser. Within the strong field approximation and considering the periodicity and symmetry of the transition matrix we show that the photoelectron spectrum can be described from the contribution during only one (or half) infrared cycle. These symmetry and periodicity properties impress selection rules which destructively cancel certain sideband orders favoring others. In particular, we analyze the photoionization of Argon in four geometrical arrangements of the polarization vector and the photoelectron momentum direction.
Photo-processing of astro-PAHs
Authors: Joblin C , Wenzel G , Rodriguez Castillo S , Simon A , Sabbah H , Bonnamy A , Toublanc D , Mulas G , Ji M , Giuliani A , Nahon L 
Published: June 2020

Abstract
Polycyclic aromatic hydrocarbons (PAHs) are key species in astrophysical environments in which vacuum ultraviolet (VUV) photons are present, such as star-forming regions. The interaction with these VUV photons governs the physical and chemical evolution of PAHs. Models show that only large species can survive. However, the actual molecular properties of large PAHs are poorly characterized and the ones included in models are only an extrapolation of the properties of small and medium-sized species. We discuss here experiments performed on trapped ions including some at the SOLEIL VUV beam line DESIRS. We focus on the case of the large dicoronylene cation,

C

48

H

20

+

, and compare its behavior under VUV processing with that of smaller species. We suggest that C2 H2 is not a relevant channel in the fragmentation of large PAHs. Ionization is found to largely dominate fragmentation. In addition, we report evidence for a hydrogen dissociation channel through excited electronic states. Although this channel is minor, it is already effective below 13.6 eV and can significantly influence the stability of astro-PAHs. We emphasize that the competition between ionization and dissociation in large PAHs should be further evaluated for their use in astrophysical models.
Merged beam studies of mutual neutralization at subthermal collision energies
Authors: Urbain X. , de Ruette N. , Dochain A. , Launoy T. , Nascimento R.F. , Kaminska M. , Stockett M.H. , Loreau J. , Liévin J. , Vaeck N. , Thomas R.D. , Schmidt H.T. , Cederquist H. 
Published: June 2020

Abstract
We have measured the kinetic energy distributions for the mutual neutralization of a large ensemble of atomic anions and cations. Ions are accelerated to equal velocities in a merged beam setup, enabling measurements at collision energies as low as 5 meV. Three-dimensional momentum imaging is performed with two position sensitive detectors located several meters downstream from the few centimeter long region where the beams overlap. An unprecedented resolution in the kinetic energy release (KER) spectra allows us to identify the states of both reactants and products down to their fine structure. Knowing the angular distribution of the products in the laboratory and center-of-mass frame, allows for total, partial, and differential cross sections to be retrieved.
On the highly charged ion transmission spectroscopy applied to 2D materials
Authors: Wilhelm Richard A. 
Published: June 2020

Abstract
The interaction of ions with solid materials may lead to charge exchange. Previous results show that charge exchange is confined to the uppermost surface layers of a solid or to the thickness of a freestanding 2D material, even when initially highly charged ions are used. Several processes are active during charge exchange and a clear distance or impact parameter dependence is observed. Here I show, that highly charged ion transmission can be used to determine the material structure of 2D materials especially when atomically resolved electron microscopy cannot be applied. The method is based on measurement of energy-, charge-, and angle-resolved ion transmission spectra in coincidence and a comparison with a local model for a time-dependent change in the projectile’s electron occupation and consequently the scattering potential. Also necessary experimental procedures are discussed.
Polarisation Effects in Above-Threshold Ionisation of Excited Helium
Authors: Bray A C , Maxwell A S , de Morisson Faria C Figueira , Kissin Y , Ruberti M , Khokhlova M , Averbukh V 
Published: June 2020

Synopsis
We present work on the disentanglement of core dynamics and binding potential influences for Above-Threshold Ionisation in Helium prepared in an excited p state, interacting with a mid-IR field. This was formed by comparing the Coulomb Quantum-Orbit Strong-Field Approximation (CQSFA) with B-spline Algebraic Diagrammatic Construction (ADC) simulations. This may lead to the identification of initial momentum distributions, for tunneling and re-scattering instances, from the CQSFA perspective. The latter method is an inverse approach; thus, the ADC simulations will allow comparison of findings.
Atomic RABBITT-like experiments assisted by a circularly polarized laser
Authors: Boll D I R , Fojón O A 
Published: June 2020

Synopsis
We study theoretically the single ionization of atoms by the combined action of an attosecond pulse train with linear polarization and an assistant laser field with circular polarization. By means of a non-perturbative model, we obtain closed-form expressions for the angular distributions of photoelectrons. We show that such a configuration of light fields is similar to the usual polarization control technique where both the attosecond pulse train and the assistant laser field are linearly polarized with a controlled relative orientation.
RABBITT attoclock for the direct measurement of ionization phases
Authors: Donsa S , Douguet N , Burgdörfer J , Březinová I , Argenti L 
Published: June 2020

Synopsis
We use a circularly polarized attosecond pulse train (APT) together with a weak replica of the fundamental circularly polarized infra-red (IR) field to reconstruct the ionization phase of the dipole allowed (2s2p)1P° resonance in atomic helium by analyzing the momentum distribution of the ionized photoelectrons within the polarization plane.
Can we break the symmetry along the polarization axis in photoionization?
Authors: Cheng Y-C , Mikaelsson S , Nandi S , Rämisch L , Guo C , Harth A , Vogelsang J , Miranda M , Arnold C L , L’Huillier A , Gisselbrecht M 
Published: June 2020

Synopsis
Photoionization is a fundamental process in which an electron is emitted from an atom. The emission is traditionally considered to be symmetric with respect to the polarization axis, unless it is temporally confined to a period shorter than an optical cycle time. We demonstrate that this symmetry can still be broken by combining a train of a few attosecond pulses and a dressing laser field. The light fields act as temporal slits and phase modulator that releases electron wavepackets. The resulting photoelectron spectra differ for electrons emitted in opposite direction along the polarization.
Attosecond XUV-pump/XUV-probe spectroscopy of glycine
Authors: Lara-Astiaso M , Palacios A , Delgado J , González-Vázquez J , Decleva P , Martín F 
Published: June 2020

Synopsis
We theoretically describe the outcome of an attosecond XUV pump-probe experiment in the smallest amino acid, glycine. We accurately evaluate the ionization amplitudes for the pump and the probe pulses. The molecular wave packet is then time-propagated using a trajectory-based Surface Hopping approach, accouting for the momentum distributions of the nuclei. Experimentally measurable photoelectron spectra are retrieved.
H2 photoionization induced by XUV pulses and X-ray free electron lasers
Authors: Sopena A , Palacios A , Martín F , Catoire F , Bachau H 
Published: June 2020

Synopsis
We present a theoretical study on H2 photionization taking into account coupled electron-nuclear motion and non-dipole effects. In the first part we study the effects of harmonic filtering in a pump-probe scheme using attosecond train pulses (ATP) in dipole approximation. In the second part we investigate nondipole effects in XUV and soft X-ray regimes.
Dynamical origin of below-threshold harmonic generation of diatomic molecules
Authors: Li P-C , Zhou X-X , Chu S-I 
Published: June 2020

Synopsis
We present an ab initio quantum study of below-threshold harmonic generation (BTHG) from H2
+ molecules in the presence of an intense laser field by solving the time-dependent Schrödinger equation accurately in space and time. We find that multiple channels contribute to BTHG of H2
+ molecules, which are related to the electron driven initially at specific time of the laser pulse from one nuclear core to another nuclear core or back to the parent core itself. The distinct contributions of these channels are distinguished by using a novel synchro squeezing time-frequency analysis.
Ultrafast imaging of the Renner-Teller effect in a field-dressed molecule
Authors: Amini K , Steinle T , Sclafani M , Shaikh M , Sanchez A , Liu X , Le A T , Steinmetzer J , Pfeiffer T , Moshammer R , Ullrich J , Lewenstein M , Moszynski R , de Abajo J G , Lin C D , Gräfe S , Biegert J 
Published: June 2020

Synopsis
We present experimental results of linear-to-bent transition of field-dressed molecules, mediated by Renner-Teller effect. Using the state-of-the-art laser-induced electron diffraction (LIED) technique, we image a bent and symmetrically stretched carbon disulfide (CS2) molecule populating an excited electronic state under the influence of strong laser field. Our findings are well-supported by ab initio quantum mechanical calculations.
Experimental comparison of frustrated tunnel ionisation in multi-cycle and few-cycle pulses
Authors: Chetty D , Glover R D , Xu H , Palmer A J , deHarak B A , Light P S , Luiten A N , Litvinyuk I V , Sang R T 
Published: June 2020

Synopsis
We present the first experimental evidence which qualitatively shows that frustrated tunnel ionization results in a larger number of excited neutrals per a tunnelling event for 6 fs pulses compared to 30 fs pulses. In addition, we also observe a less severe dependence on elliptical polarization for the 6 fs pulses. Furthermore, by varying the carrier envelope phase of the shorter pulse, we observe a modulation in the yield of excited neutrals which indicates possible control of electron trajectories.
Real-time reconstruction of the strong-field driven dipole response
Authors: Stooß V , Cavaletto S M , Donsa S , Blättermann A , Birk P , Keitel C H , Březinová I , Burgdörfer J , Ott C , Pfeifer T 
Published: June 2020

Synopsis
Using ultrashort and phase-locked laser pulses, combined with an in situ measurement of a reference pulse, we present a method capable of retrieving the nonlinearly perturbed time-dependent response function of a quantum system driven by strong electric fields directly from spectroscopic absorption data with high precision.
Revealing the multiorbital and excitation effects in dissociative double ionization of CO molecules with angular streaking measurement
Authors: Li X , Yu J , Yu X , Yang Y , Wang C , Luo S , Ding D 
Published: June 2020

Synopsis
We investigate the sequential double ionization dynamics for the dissociative channel C+ + O+ of CO molecules in strong circularly polarized laser fields. By using four-particle coincident measurement, the obtained ionic angular emissions and molecular frame photoelectron angular distributions of each ionization steps for various pathways reveals the significant effects of multiorbital ionization and laser-driven excitation.
Laser-assisted electron scattering and ionization processes in a quasi-Sturmian-Floquet approach
Authors: Zaytsev S A , Zaytsev A S , Ancarani L U , Kouzakov K A 
Published: June 2020

Synopsis
We demonstrate the robustness and efficiency of our recently formulated quasi-Sturmian-Floquet method to treat light-dressed electron states. For this purpose we study the archetypical processes such as laser-modified electron scattering on a Coulomb potential and laser-assisted electron-impact ionization of atomic hydrogen. For both processes we explore various regimes of laser radiation and identify the differences with respect to the corresponding laser-free situations.
Complex permittivity and permeability properties analysis of NiCuZn Ferrite-Polymer nanocomposites for EMI suppressor applications
Authors: Raju P , Shankar J , Anjaiah J , Kalyani Ch , Neeraja Rani G 
Published: June 2020

Abstract
The complex permittivity and permeability studies of NiCuZn ferrite-paraformaldehyde (NCZ-PFD) nanocomposites for electromagnetic interference (EMI) suppressor applications are presented. The NCZ Ferrite and nanocomposites were prepared via microwave hydrothermal and ball-milling, respectively. The nanocomposites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) the results indicate that the NCZ-PFD nanocomposites were successfully prepared without impurities. The complex permittivity and permeability were measured over frequency range of 8.2-12.4 GHz and 12.4–18 GHz. The results show that for nanocomposites, the values of the real (ε′) and imaginary permittivity (ε″) and imaginary permeability (μ″) increase, while the value of real permeability (μ′) decreases as the polymer content increases. Dielectric relaxations were studied using cole-cole plots of complex permittivity. Magnetic relaxation dispersions were analyzed using cole-cole plots of complex permeability. The possibility to modulate the electromagnetic properties of the composite materials is of a great interest to fabricate microwave absorbing and electromagnetic shielding materials with high performances.
Dielectric, Magnetic and Spectral studies of gel grown Mg2+ Doped Copper Cadmium Oxalate Single Crystals
Authors: Rohith P S , Jagannatha N , Pradeepkumar K V , Mangala M S 
Published: June 2020

Abstract
Mg2+ doped Copper Cadmium oxalate (MCuCO) single crystals were grown by a single diffusion method in silica hydrogel at room temperature. Powder X-ray diffraction (XRD) studies show the triclinic nature of the crystals. The dielectric constant, ac resistivity and ac conductivity have been measured as a function of frequency. The dielectric constant of MCuCO crystal decreases as the frequency of applied field increases; at the end it gives the diminishing value of dielectric constant. AC conductivity increases with the increase of frequency. Absorbance, transmittance, reflectance, refractive index, and energy gap of MCuCO crystal were determined by UV-Visible spectroscopy. A high bandgap corresponds to the dielectric behavior of the crystal.