bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma dynamic simulations for reducing the erosion of discharge channel walls of Hall Effect Thruster (HET)
Authors: Priyanka B , Asif M M , Umesh R K 
Published: June 2020

Synopsis
To assess and improve the design aspects during the design and development of HETs, it is essential to perform plasma dynamic simulations on these thruster designs. A 2D-3V (two dimensional-three velocity) Particle-in-cell Monte Carlo (PIC-MC) model has been used to simulate the standard SPT-100, and the design was optimized. Later, a completely new HET geometry has been simulated with an aim to optimize the thruster design with reduced plasma wall interaction.
Identification of EUV spectral profiles of laser-produced Cr plasmas
Authors: Wu L , Su M G , Min Q , Cao S Q , He S Q , Sun D X , Dong C Z 
Published: June 2020

Synopsis
Laser-produced chromium (Cr) plasmas have been measured by using a temporal-spatially resolved laser-produced plasma emission spectroscopy technique. The emission peaks in the wavelength range of 6.5-15 nm were identified from the 3p-4d, 5d, and 3p-4s transition lines from Cr5+ to Cr10+ ions with aid of Cowan and Flexible Atomic Code (FAC) atomic structure calculations, and through comparative analysis between experimental and simulated spectra.
Evidence of trielectronic recombination for Ar ions in an EBIT
Authors: La Mantia D S , Biela W , Tanis J A , Warczak A 
Published: June 2020

Synopsis
Trielectronic recombination has been investigated for Ar ions in a compact, room-temperature electron beam ion trap. A significant increase in hollow-core emission has been observed at the expected beam energy (~ 6.4 keV) for the KK→LMM resonance transition.
Absolute vibrational and electronic cross sections for low-energy electron scattering from condensed Thymidine
Authors: Lemelin V , Bass A D , Sanche L 
Published: June 2020

Synopsis
Absolute vibrational and electronic excitation cross sections (CSs) for low-energy electrons (1-18 eV) scattering from condensed thymidine (dT) are measured with High-Resolution Electron Energy Loss Spectros-copy (HREELS). EEL spectra are recorded and the vibrational and electronic modes of dT identified. Absolute CSs for these modes are extracted from each spectrum by a fitting procedure. Resonances are observed in the incident energy dependence of the CSs, below 3 eV and near 4, 8 and 10 eV. The CSs are compared to those of its constituents: thymine and tetrahydrofuran.
Observation of two-electron one-photon X-ray transitions in collisions of slow Xe26+ ions with beryllium surface
Authors: Jabłoński Ł , Banaś D , Jagodziński P , Kubala-Kukuś A , Sobota D , Stabrawa I , Szary K , Pajek M 
Published: June 2020

Synopsis
Two-Electron One-Photon (TEOP) X-ray transitions were observed for the first time in collisions of highly charged Xe ions with metallic Be surface. The intensities of TEOP X-rays are well described by performed MCDF for one-electron one-photon (OEOP) dipole-allowed transition of Paschen and Brackett series assuming constant TEOP/OEOP branching ratio. The importance of the Internal Dielectronic Excitation (IDE) in relaxation of hollow Xe ions/atoms has been evidenced and discussed.
Phonon contribution to grazing incidence fast atom diffraction
Authors: Gravielle M S , Miraglia J E 
Published: June 2020

Synopsis
We address the effect of lattice vibrations of the crystal on grazing incidence fast atom diffraction (GIFAD) from insulator surfaces. To describe the phonon contribution to GIFAD we introduce a semi-quantum method, named Phonon-Surface Initial Value Representation (P-SIVR), which represents the surface with a harmonic crystal model, while the scattering process is given by the Surface Initial Value Representation approach including phonon excitations. P-SIVR results for Ne/LiF(001) are compared with other theoretical methods and available experiments.
Highly charged ion impact on graphene leading to the emission of low energy electrons
Authors: Schwestka J , Niggas A , Creutzburg S , Kozubek R , Madauß L , Heller R , Schleberger M , Facsko S , Wilhelm R A , Aumayr F 
Published: June 2020

Synopsis
Recent experiments found that the neutralisation of highly charged ions interacting with a freestanding single layer of graphene proceeds on a femtosecond time scale. This ultra-fast deexcitation was attributed to Interatomic Coulombic Decay (ICD), a process in which core holes in the projectile are filled by previously captured outer electrons and the energy is transferred to electrons of the surrounding carbon atoms. ICD therefore predicts the emission of many low energy electrons. We now present experimental evidence that e.g. Xe40+ indeed emits up to 85 electrons with energies below 20 eV.
Energy selective time of flight spectrometer to study low energy dissociation channels of PAHs
Authors: Vinitha M V , Kadhane U 
Published: June 2020

Synopsis
Dissociation channels induced by sequential UV multiphoton absorption of vapour phase fluorene cation is investigated using energy selective ToF mass spectrometer. Neutral fluorene molecule is ionized by resonantly enhanced multiphoton absorption and dissociated in the same photon field. The main goal of this experiment is to determine the rate constants of statistical dissociation channels of PAH cations for a wide range of internal energies.
Radiodosimetry endpoints obtained with the TILDA-V Monte Carlo tracking structure code
Authors: Quinto M A , Alcocer-Avila M E , Monti J M , Weck P F , Fojón O A , Rivarola R D , Champion C 
Published: June 2020

Synopsis
The present study aims at scrutinizing at the nanometer scale the radiodosimetry endpoints induced by ion beams in a realistic biological medium. In this context, self-consistent quantum mechanical modeling of the ionization and the electron capture processes are reported within the continuum distorted wave-eikonal initial state (CDW-EIS) framework for both isolated water molecules and DNA components impacted by ions.
State-dependent fragmentation of protonated uracil and uridine
Authors: Pitzer M , Ozga Ch , Küstner-Wetekam C , Reiß Ph , Knie A , Ehresmann A , Jahnke T , Giuliani A , Nahon L 
Published: June 2020

Synopsis
Protonated uracil (m/z 113) and uridine (m/z 245) were exposed to synchrotron radiation in the photon energy range of 4.5 to 9 eV. The yield of various fragments as a function of photon energy shows maxima that can be attributed to excited electronic states and compared to calculated vertical excitation energies. For the nucleoside uridine, much less fragments were observed, indicating a stabilization of the nucleobase through the attached sugar molecule.
Convergent close-coupling calculations of positron collisions with the hydrogen negative ion
Authors: Fursa D V , Utamuratov R , Kadyrov A S , Bray I 
Published: June 2020

Synopsis
Convergent close-coupling method has been applied to positron scattering by the hydrogen negative ion. Internal consistency of the method and convergence of the cross sections are achieved with use of both the single- and two-centre approaches. Calculations were performed using accurate target wave functions obtained with the multi-core approach.
Towards investigations of pre-cooled ions stored in the RICE storage ring via action spectroscopy
Authors: Chartkunchand KC , Menk S , Hirota A , Igosawa R , Kuma S , Nakano Y , Azuma T 
Published: June 2020

Synopsis
A new cryogenic linear ion trap beamline has been commissioned for use with the RIKEN Cryogenic Electrostatic (RICE) storage ring. Testing of the beamline at room-temperature and cryogenic conditions was conducted using methylene blue cations MB+ and carbon cluster anions Cn
−. Action spectroscopy measurements of pre-cooled Cn
− anions injected into RICE will help determine the effectiveness of the so-called Pre-Trap Beamline, as well as provide structural and dynamical information on these cluster anions at cryogenic temperatures.
Final state resolved mutual neutralization of Li+ and D−
Authors: Eklund G , Grumer J , Rosén S , Najeeb P K , Zettergren H , Cederquist H , Barklem P S , Schmidt H T 
Published: June 2020

Synopsis
We have performed a merged beam experiment on mutual neutralization of Li+ and D−, at center of mass energies close to 0 eV using the DESIREE storage rings. The final state channels Li(3s) and Li(3p+3d) are resolved and the branching ratio is found to be more equal than predicted from theoretical models.
Development of a detector to register low-energy, charge-changed ions from ionization experiments at CRYRING@ESR
Authors: Borovik A , Weber G , Hilbert V , Lin H , Pfäfflein P , Zhu B , Hahn C , Lestinsky M , Schippers S , Stöhlker Th , Rothhardt J 
Published: June 2020

Synopsis
A detector setup for registering ion species between the poles of a dipole magnet at CRYRING@ESR has been developed. It is based on a scintillator delivering light via a quartz light guide onto a semiconductor photomultiplier. The detector is capable of operating in a strong magnetic field. It can be swiftly retracted from the exposition area during the beam injection into the ring and repositioned back for the measurement cycle to avoid unnecessary exposition and, thus, to increase the scintillator life time.
Precision Measurements of the Fundamental Properties of the Proton and Antiproton
Authors: Smorra C. , Mooser A. 
Published: June 2020

Abstract
Precision measurements comparing the fundamental properties of conjugate particles and antiparticles constitute stringent tests of CPT invariance. We review recent precision measurements of the BASE collaboration, which improved the uncertainty of the proton and antiproton magnetic moments and the comparison of the proton-to-antiproton charge-to-mass ratio. These measurements constitute the most stringent tests of CPT invariance with antiprotons. Further, we discuss the improved limit on the antiproton lifetime based on the storage of a cloud of antiprotons in the unique BASE reservoir trap. Based on these recent advances, we discuss ongoing technical developments which comprise a coupling trap for the sympathetic cooling of single (anti-)protons with laser-cooled beryllium ions, a transportable trap to relocate antiproton measurements into a high-precision laboratory, and a new experiment to measure the magnetic moment of helium-3 ions, which will improve absolute precision magnetometry.
Machine learning for analysing ab initio molecular dynamics simulations
Authors: Häse Florian , Galván Ignacio Fdez. , Aspuru-Guzik Alán , Lindh Roland , Vacher Morgane 
Published: June 2020

Abstract
Post-calculation analyses are often required to extract physical insights from ab initio molecular dynamics simulations. In the present work, we use different machine learning classifiers to take a new perspective on the decomposition reaction of dioxetane. Upon thermally activated decomposition, dioxetane can form products in an electronically excited state and can thus chemiluminesce. Simulated dynamics trajectories exhibit both successful and frustrated dissociations. As an exhaustive and systematic study of the decomposition mechanism “by hand” is beyond feasibility, machine learning models have been employed to study the relevant nuclear distortions governing molecular dissociation. According to all classifiers used in the study, the two sets of geometries differ by the in-phase planarisation of the two formaldehyde moieties. New insights are obtained from this analysis: if both moieties are not planar enough when the dissociation is attempted, it is frustrated and the molecule remains trapped. The postponing of the decomposition reaction by the so-called entropic trap enhances the chemiexcitation efficiency.
Positron collisions with targets of biological and technological relevance
Authors: Barbosa Alessandra Souza , Sanchez Sergio D’A , Bettega Márcio H F 
Published: June 2020

Abstract
In this work we present calculated cross sections for elastic scattering of low-energy positrons by molecules, obtained with the Schwinger multichannel method. We extended a previous study on the role of polarization effects in the positron-allene scattering and also present some preliminary results for positron collisions with cyclopentane. We also compare the differential cross sections of benzene and its azaderivative pyrimidine at selected energies, where similar angular behaviour was found.
Selective bond scission in formic acid by low-energy electrons
Authors: Griffin Brandon , Moradmand Ali , Williams Joshua , Belkacem Ali , Rescigno Thomas N , Trevisan Cynthia , McCurdy C William , Weber Thorsten , Slaughter Daniel S 
Published: June 2020

Abstract
We report recent results of mass-resolved anion fragment momentum imaging experiments to investigate dissociative electron attachment to formic acid, for incident energies between 5 eV and 9 eV. A remarkable site-selectivity is found for a resonance at 8.5 eV by comparing anion fragment yields for two deuterated isotopologues of formic acid. This results in an H− fragment from the O-H bond of the transient anion, with negligible contribution from C-H break. In contrast, a lower-energy resonance at 7.1 eV dissociates by C–H or O–H break to produce H− and the neutral radicals HOCO or HCOO.
Electron attachment and quantum coherence in molecular hydrogen
Authors: Prabhudesai Vaibhav S , Mason Nigel J , Krishnakumar E 
Published: June 2020

Abstract
Single electron attachment to a molecule may invoke quantum coherence in different angular momentum transfer channels. This has been observed in the 14 eV dissociative electron attachment resonance in molecular hydrogen where a coherent superposition of two negative ion resonant states of opposite parity is created, with the s and p partial waves of the electron contributing to the attachment process. Interference between the two partial wave contributions leads to a forward – backward asymmetry in the angular distribution of the product negative ions. Since these two resonant states dissociate to the same n = 2 state of H and H−, this asymmetry is further modified due to interference between the two paths of the dissociating molecular negative ion along different potential energy curves. This interference manifests as a function of the electron energy as well as isotopic composition. This case is akin to the quantum interference observed in photodissociation by one-photon vs two-photon absorption.
Positronium collisions with atoms and molecules
Authors: Wilde R S , Fabrikant I I 
Published: June 2020

Abstract
We describe recent theoretical efforts to explain the observed similarity between electron and positronium (Ps) scattering with both atoms and molecules. In order to perform these calculations at a more ab initio level we have developed a Free Electron Gas (FEG) approximation to the exchange and correlation potentials similar to that used in electron-molecule scattering. The FEG results give good agreement with experiment above the Ps ionization threshold and exhibit resonance features below the threshold. To take account of the effect of orthogonality between the scattered electron and the target wavefunctions we have used an orthogonalizing pseudopotential (OPP). The FEG plus OPP results give good agreement with experiment for Ps-rare-gas scattering. Preliminary results for Ps-H2 scattering also agree well with experiment and demonstrate the importance of including orthogonality for scattering below the Ps ionization threshold.
Projectile Coherence Effects in Simple Atomic Systems
Authors: Schulz M , Hasan A , Lamichhane B , Arthanayaka T , Dhital M , Bastola S , Nagy L , Borbély S , Járai-Szabó F 
Published: June 2020

Abstract
Recent studies of projectile coherence effects in ion-atom collisions are presented. For intermediate-energy proton collisions an extensive literature provides strong support for the importance of such effects. In this regime coherence effects are now used as a tool to study the few-body dynamics very sensitively. In contrast, for high-energy ion impact the literature is much sparser and here an important role of coherence effects cannot be regarded as being established. In this context, a recent claim that in COLTRIMS experiments the coherence properties are determined only by the target beam is rebutted.
An introduction to Bayesian statistics for atomic physicists
Authors: Trassinelli M. 
Published: June 2020

Abstract
We present an introduction to some concepts of Bayesian data analysis in the context of atomic physics. Starting from basic rules of probability, we present the Bayes’ theorem and its applications. In particular we discuss about the limits of classic statistics methods and in which cases a Bayesian analysis is mandatory. Moreover, we show how probability values can be assigned to different possible models (different numbers of peaks, type peak profile, etc.) from the analysis of experimental data.
Disentangling spectral phases of interfering autoionizing states from attosecond interferometric measurements
Authors: Petersson C L M , Barreau L , Klinker M , Camper A , Marante C , Gorman T , Kiesewetter D , Argenti L , Agostini P , González-Vazques J , DiMauro L F , Salières P , Martín F 
Published: June 2020

Synopsis
The spectral phase of the autoionising neon continuum has been probed via interferometric pump-probe measurements as well as ab initio, full-electron, time-dependent, theoretical calculations in energy intervals containing several auto-ionising. Theory and experiment are in excellent agreement. Despite the complex energy-dependence of the phase, a very simple model has been used to disentangle the contribution by different resonances. This work extends the applicability of reconstruction methods to multi-resonance regions of autoionising continua - a common scenario in multi-electron systems.
Phase reconstruction of high-order harmonics by quantum path interference
Authors: Olofsson A , Ibrakovic N , Ek S , Bengtsson S , Simpson E R , Mauritsson J 
Published: June 2020

Synopsis
We present a method to retrieve the phase of XUV light generated through high-order harmonic generation, by observing the intensity dependence of the interference pattern in the far-field. This interference pattern arises from electron trajectories in the generation process. These trajectories spend different time in the continuum and the phase of the generated light will therefore depend differently on the instantaneous intensity of the driving field. By changing the intensity of the driving field the phase of the contributing trajectories can be extracted.
Sideband selection in XUV + IR photoionization
Authors: Picca R Della , Gramajo A A , López S D , Arbó D G 
Published: June 2020

Synopsis
We consider the ionization of argon atoms induced by a femtosecond laser pulse composed by overlapping extreme ultraviolet and infrared fields. We study several geometrical arrangements within the polarization vectors and emission direction that determinate only odd or even sideband peaks are present in the photoelectron spectrum.
Atomic and molecular suite of R-matrix codes for ultrafast dynamics in strong laser fields and electron/positron scattering
Authors: Wragg J , Benda J , Mašín Z , Armstrong G S J , Clarke D D A , Brown A C , Ballance C , Harvey A G , Houfek K , Sunderland A , Plummer M , Gorfinkiel J D , van der Hart H 
Published: June 2020

Synopsis
We describe and illustrate a number of recent developments of the atomic and molecular ab initio R-matrix suites for both time-dependent calculations of ultrafast laser-induced dynamics and time-independent calculations of photoionization and electron scattering.
Temporal metrology for advanced ultrashort XUV sources
Authors: Sinyakova T , Bomme C , Bourassin-Bouchet C , Chopineau L , Cubaynes D , Dakroub L , Garcia G , Pandey A , Papagiannouli E , Guilbaud O , Quéré F , Klisnick A 
Published: June 2020

Synopsis
A new VMI spectrometer has been developed in order to enable the single-shot characterization of different ultrashort XUV sources through laser-dressed photoionization. The instrument has been commissioned with a plasma-based XUV laser and, then, implemented on a high harmonics source based on a plasma mirror.
Generation and characterization of isolated attosecond pulses for coincidence spectroscopy at 100 kHz repetition rate
Authors: Witting T , Furch F , Osolodkov M , Schell F , Menoni C , Schulz CP , Vrakking M J J 
Published: June 2020

Synopsis
An attosecond pump-probe beamline with 100 kHz repetition rate for coincidence experiments has been developed. It is based on non-collinear optical parametric chirped pulse amplification and delivers 100 μJ sub-4 fs to an high-harmonic generation source. Details on the generation and characterization of isolated attosecond pulses will be presented.
Attosecond angular streaking on H2 with all-ionic fragments detection
Authors: Quan W , Zhao M , Serov VV , Wei M Z , Zhou Y , Lai X Y , Kheifets A S , Liu X J 
Published: June 2020

Synopsis
We explore a novel attosecond angular streaking scheme on H2 based on the all-ionic dissociative fragments detection. We aim to reveal the same information from the ionic attoclock as extracted from conventional attoclock measurements [1]. We examine the validity of the axial recoil approximation questioned in [2]. The advantage of the proposed scheme is that it does not rely on the adiabatic electron tunneling hypothesis which has raised the ongoing controversy of a finite tunneling time in the attosecond community [3]
Gauge-invariant time-dependent configuration interaction singles method: applications to high-harmonic generation from atoms
Authors: Teramura T , Sato T , Ishikawa K L 
Published: June 2020

Synopsis
We present gauge-invariant reformulation of time-dependent configuration interaction singles (TDCIS) method and its applications to high-harmonic generation (HHG) from three-dimensional atoms. The conventional TDCIS method suffers from a violation of gauge-invariance, which prevents efficient simulations of high-field phenomena within the velocity gauge. In our reformulation, rotated velocity gauge transformed from the length gauge is employed instead of the velocity gauge. We simulate HHG from atoms and show gauge-invariance and performance of our rotated velocity gauge.
Two-photon laser-assisted electron scattering on Hydrogen atom
Authors: Kornev A S , Zon B A 
Published: June 2020

Synopsis
We considered the influence of light-dressed-atom effect on two-photon laser-assisted electron-atom scattering in the Born approximation. We performed calculations for the ground state of a Hydrogen atom. For small scattering angles, the main contribution to the cross section is made by the combined process, when one of the photons is absorbed by the atomic electron and the second one by the scattered electron. However, in the UV region, when two-photon resonances with highly excited atomic states arise, the main contribution is determined by the inverse polarization Bremsstrahlung absorption.
Dynamic photoemission interference of hydrogen atoms in intense ultra-fast elliptically polarized extreme ultraviolett pulses
Authors: Li G , Wang N , Wang J , Liu A , Thumm U 
Published: June 2020

Synopsis
We investigated dynamic interference (DI) in the photoionization of ground-state hydrogen atoms by intense extreme-ultraviolet (XUV) pulses with elliptical polarization. Numerically solving the time-dependent Schrodinger equation, we demonstrate that DI occurs not only in linearly but also in elliptically polarized pulses.