bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic diagnostics of ultrahigh laser intensities
Authors: Ciappina M F , Popruzhenko S V , Korn G , Ditmire T , Bulanov S V , Weber S
Published: June 2020

Synopsis

We suggest and discuss a method for precise measurement of ultrahigh laser intensities in the 1020 – 1024W/cm2 range of intensities. The method is based on the observation of multiple sequential tunneling ionization of heavy atoms in the focus of an intense laser beam. It can be of use for probing electromagnetic fields of record power expected to achieve at new multi-petawatt laser facilities.
Target dependence of post-collision effects in ionization by proton impact
Authors: Silvus A , Dhital M , Bastola S , Buxton J , Klok Z , Ali E , Ciappina M F , Madison D H , Schulz M
Published: June 2020

Synopsis

Double differential cross sections (DDCS) for ionization in p + Ne, Ar collisions were measured and calculated for a broad range of projectile energy losses as a function of scattering angle. PCI effects in the DDCS were found to be become increasingly prominent with increasing ionization potential I probably due to a greater importance of the nucleus-nucleus interaction when I becomes larger.
First experimental results from a new high-power electron gun: Electron-impact ionisation of multiply charged xenon ions
Authors: Döhring B M , Ebinger B , Borovik A , Huber K , Müller A , Schippers S
Published: June 2020

Synopsis

During recent years we have developed a new high-current electron gun for the Giessen electron-ion crossed-beams experiment aiming at an extension of the previously available collision-energy range of 1–1000 eV to 3500 eV. Here, we report on the first measurements of absolute cross sections for electron-impact ionisation of multiply charged xenon ions employing the new electron gun. Comparisons with available experimental and theoretical data from the literature provide convincing evidence that the new electron gun can be operated reliably over the entire design energy-range.
Role of the variable charge in (e,3e) processes on argon
Authors: Herbadji A , Mansouri A , Dal Cappello C , Kada I , Houamer S
Published: June 2020

Synopsis

The differential fivefold cross section for the double ionization of argon by electron impact is calculated taking into account the variations of the effective charges describing each ejected electron during the reaction; the energy of the electron projectile is fixed in the intermediate range, and the ejected electrons have low energies. The initial state is described by the Clementi wavefunction, and the ejected electrons in the final state by Coulomb waves. A comparison is made with the measurements of Jia et al [1].
Electron-impact ionisation of Wq+ ions with 1 ⩽ q ⩽ 19
Authors: Schury D , Becker A , Borovik A , Ebinger B , Gharaibeh M F , Hellhund J , Huber K , Rausch J , Spruck K , Jin F , Schippers S , Müller A
Published: June 2020

Synopsis

Electron-impact ionisation cross sections of tungsten ions in the energy range from the ionisation threshold to 1000 eV were measured. The experimental cross sections are compared with results from sub-configuration averaged distorted wave calculations. Derived plasma rate coefficients are provided for convenient use in plasma modelling.
Tracing inter-Coulombic decay of molecular dimers
Authors: Iskandar W , Gatton A S , Gaire B , Sturm F P , Larsen K A , Champenois E G , Shivaram N , Moradmand A , Williams J B , Berry B , Severt T , Ben-Itzhak I , Metz D , Sann H , Weller M , Jahnke T , Dörner R , Slaughter D , Weber Th
Published: June 2020

Synopsis

We have conducted an experimental study on the photo double ionization (PDI) of carbon dioxide dimers and oxygen dimers, while focusing on the dissociation dynamics upon single photon absorption. The results in terms of the kinetic energy and angular distributions of the charged particles show unambiguous experimental evidence of intermolecular Coulombic decay (ICD) in carbon dioxide dimers. In the oxygen dimer, the results show that ICD is accompanied by knock-off ionization mechanisms.
Effect of SOIAIC on photoionization time delay of the Xe 3d subshell
Authors: Banerjee S , Deshmukh P C , Manson S T
Published: June 2020

Synopsis

The effect of spin-orbit activated interchannel coupling (SOIAIC) has been studied on the time delay spectrum of 3d photoionization in xenon. The relativistic-random-phase-approximation with relaxation (RRPA-R) has been used to calculate the Wigner-Eisenbud-Smith (WES) time delay in photoionization. SOIAIC has a strong influence on the WES time delay for all ejection angles of the photoelectrons with respect to the incident direction and the polarization vector of the photon absorbed.
Outer-shell photodetachment of Li− near inner-shell thresholds
Authors: Gorczyca T W , Manson S T
Published: June 2020

Synopsis

The effect of inner-shell excited channels on outer-shell photodetachment is investigated using a correlated and coupled-channel R-matrix method. The simplest multishell negative ion of Li− is treated near the 1s ionization threshold to determine strong”hole-state” continuum coupling with the direct photodetachment channels.
Using ‘dressed’ convoluted quasi-Sturmian functions as a basis for Coulomb three-body continuum problems
Authors: Zaytsev A S , Zaytseva D S , Ancarani L U , Zaytsev S A
Published: June 2020

Synopsis

We present an ab initio approach to the two electron continuum problem based on an expansion on convoluted quasi Sturmian functions (CQS) equipped with an appropriately built electron-electron phase factor. Such’dressed’ CQS functions constitute a suitable basis to solve Coulomb three-body scattering problems as illustrated through numerical applications to double ionization processes on Helium. They put in evidence, once more, the importance of electron-electron correlation over the whole space.
Energy dependent relative cross sections in carbon 1s photoionization
Authors: Travnikova O , Patanen M , Söderström J , Lindblad A , Kas J J , Vila F D , Céolin D , Nicolas C , Marchenko T , Goldsztejn G , Journel L , Guillemin R , Carroll T X , Børve K J , Decleva P , Rehr J J , Mårtensson N , Simon M , Svensson S , Sæthret L J
Published: June 2020

Synopsis

We demonstrate that the possibility of monitoring relative photoionization cross sections over a large photon energy range extending to hard x-rays allows studying and disentangling shake processes and intramolecular inelastic scattering effects. An “EXAFS”-type of oscillatory behaviour of the relative C 1s cross sections is observed in a wide photon energy range up to 1 keV due to multiple intramolecular elastic scattering of the photoelectron. These effects are also present in solids and constitute a significant part of all elastic and inelastic scattering effects occurring in solids.
Unravelling the molecular phenomena of hydrogen peroxide (H2O2) through many-body fragmentation dynamics
Authors: Nrisimhamurty M , Mandal A , Tribedi L C , Misra D
Published: June 2020

Synopsis

Ion-induced fragmentation dynamics of H2O2
3+ has been studied to distangle molecular phenomena like concerted and sequential fragmentation routes.
Photodissociation dynamics of the diamondoid adamantane induced by attosecond XUV pulses
Authors: Maclot S , Peschel J , Lahl J , Wikmark H , Rudwaski P , Coudert-Alteirac H , Rousseau P , Indrajith S , Huber B A , Díaz-Tendero S , Johnsson P
Published: June 2020

Synopsis

Adamantane is the simplest of the diamondoid molecules, which due to their high stability are of high interest both in astrophysics and nanotechnology. This work investigates the molecular photodissociation after ionization by attosecond XUV pulses. The fragmentation dynamics is inferred by means of velocity map imaging spectrometry, covariance analysis techniques and quantum chemistry calculations.
Determination of energy-transfer distributions in ionizing ion-molecule collisions
Authors: Indrajith S , Erdmann E , Chiarinelli J , Domaracka A , Łabuda M , Avaldi L , Alcami M , Aguirre N F , Díaz-Tendero S , Bolognesi P , Rousseau P , Huber B A
Published: June 2020

Synopsis

The main objective of this study is to determine the energy transfer occuring in ion-molecule collisions. In order to solve this problem, we followed two approaches; the first one by validating a purely experimental method and the second one by testing a new theoretical model M3C (Microcanonical Metropolis Monte Carlo).
Absolute cross section for electron emission from uracil upon ion collision using velocity map imaging technique
Authors: Sens N , Ryszka M , Méry A , Poully J-C , Chesnel J-Y , Vizcaino V
Published: June 2020

Synopsis

Ion-induced electron emission from RNA base uracil has been measured using a newly developed experimental set-up based on velocity map imaging (VMI) technique. Electrons emitted in a solid angle of 4π steradians are extracted and analyzed in energy and angle by the multi-electrodes VMI spectrometer. By monitoring the target density, the projectile ion beam intensity and the beams overlap with the use of a quartz crystal micro balance and an ion beam profiler, we were able to estimate absolute singly- and doubly-differential cross sections for electron emission.
A new experimental setup to measure absolute cross section for electron emis-sion from atoms, molecules or nanoparticles upon ion collisions
Authors: Sens N , Ryszka M , Mery A , Poully J-C , Chesnel J-Y , Vizcaino V
Published: June 2020

Synopsis

A newly developed crossed beam experimental setup that utilizes a velocity map imaging technique to simultaneously measure both emission energy and angle of electrons ejected from atoms, molecules or nano-particles upon ion collision will be presented. The incident ion beam is produced at the GANIL facility with incident energies from a few keV to a few MeV and the target beam density is monitored by a quartz crystal microbalance allowing for estimating absolute single or double differential cross sections.
Two-body dissociation of C3H4 isomers investigated by 50 keV/u Ne8+ impact
Authors: Li Y , Xu S , Guo D L , Jia S , Jiang X , Zhu X L , Ma X
Published: June 2020

Synopsis

Fragmentation dynamics of two isomers of C3H4, propyne (CH3CCH) and allene (CH2CCH2), is in-vestigated by 50 keV/u Ne8+ impact. Isomerization processes are identified in two-body fragmentation channels of C3H4
2+ for both isomers. Besides, we observe two new dissociation channels of C3H4
3+ trications, H+ + C3H3
2+ and H2
+ + C3H2
2+. For CH2CCH2
3+, the peak and shoulder structures in the kinetic energy release spectrum of H+ + C3H3
2+ channel are attributed to different geometries of the C3H3
2+ products by comparing with theoretical cal-culation.
Coupled-channel calculations of ionisation of atomic hydrogen by multiply-charged bare ions
Authors: Abdurakhmanov I B , Massen-Hane K , Faulkner J , Alladustov Sh U , Kadyrov A S , Bray I
Published: June 2020

Synopsis

The wave-packet convergent close-coupling method has been applied to calculate the total and fully differential cross sections for electron capture, excitation and ionisation processes in collisions between multiply-charged bare ions and atomic hydrogen.
Fragmentation of hydrocarbons by collision. AGAT@ANDROMEDE.
Authors: IdBarkach T , Chabot M , Béroff K , Della-Negra S , Lesrel J , Diaz-Tendero S
Published: June 2020

Synopsis

We are studying small hydrocarbons produced in high velocity (3.4 a.u.) collision between

CH

y
+

cations and He atoms. During the collision those hydrocarbons gain some energy and release this energy doing fragmentation. Thanks to the detector AGAT we have been able to measure fragmentation branching ratios for

CH

y

q
+

(y=2-4, q=0-3). We also constructed semi-empirical breakdown curves for

CH

y

q
+

using these experimental branching ratios.
Energy deposition of highly charged ions transmitted through single layer MoS2
Authors: Creutzburg S , Schwestka J , Inani H , Tripathi M K , Grande P L , Heller R , Klingner N , Niggas A , Kozubek R , Madauß L , Facsko S , Kotakoski J , Schleberger M , Aumayr F , Wilhelm R A
Published: June 2020

Synopsis

Highly charged ions (HCIs) are an efficient tool for the perforation of suspended 2D materials. Only a fraction of their potential energy is transferred to the atomically thin target during the very short interaction time and is available for pore formation. Charge exchange spectra were measured for highly charged xenon ions transmitted through suspended, single layer MoS2 in order to determine the deposited potential energy available for pore formation. Additionally, charge exchange dependent ion stopping responsible for kinetic sputtering was measured simultaneously.
Electronic reactive collisions in cold ionised media: from mechanisms to new state-to-state cross sections and rate coefficients
Authors: Mezei J Zs , Orbán A , Chakrabarti K , Moulane Y , Epée Epée M D , Motapon O , Talbi D , Schneider I F
Published: June 2020

Synopsis

The major mechanisms governing the dynamics of electron-driven reactions of molecular cations will be illustrated.
Low energy elastic electron scattering from benzonitrile (C6H5CN)
Authors: Tatreau G , Diaz B , Alharthi F , Zawadzki M , Khakoo M A
Published: June 2020

Synopsis

We present experimental differential elastic scattering cross sections (DCSs) for low energy electron scattering from benzonitrile along with integral and momentum-transfer cross sections that are determined from these DCSs. The measurements of DCSs are obtained using the relative flow method with helium as the standard gas, in a crossed electron-molecular gas beam arrangement. Our measurements are made at incident electron energies in the range of 1 – 30 eV and scattering angles in the range of (10°-130°).
Negative ion formation in fullerene molecules C44, C74, C100, C124 and C136: determination of their electron affinities
Authors: Msezane A Z , Felfli
Published: June 2020

Synopsis

Here we investigate through the electron elastic total cross sections (TCSs) calculations the variation of the electron affinity (EA) with the fullerene size from C44 to C136 and contrast their EAs with that of C60. The TCSs are found to be characterized generally by ground, metastable and excited anionic formation during the collisions. The extracted ground state anionic binding energies for C44, C74, C100, C124 and C136 are 3.25eV, 4.03eV, 3.67eV, 3.06 eV and 3.75eV, respectively. These corresponding to the fullerenes EAs demonstrate their wide variation.
Low energy differential elastic electron scattering from trichloromethane
Authors: Diaz B , Tatreau G , Hlousek B , Zawadzki M , Khakoo M A
Published: June 2020

Synopsis

Experimental differential cross sections for low energy electron scattering from trichloromethane is measured utilizing a crossed electron-molecular beam experiment via the relative flow method, for the incident electron energies in the range of E
0 = 0.5eV-30eV and the scattering angles in the range of θ = 10° – 130°.
Total cross section measurements for electron scattering from tin(IV) chloride (SnCl4)
Authors: Możejko P , Stafanowska-Tur S , Ptasrńska-Denga E , Szmytkowski Cz
Published: June 2020

Synopsis

Total cross section for electron scattering from SnCl4 molecules has been measured for energies from 0.6 to 300 eV. Obtained results have been compared with total cross sections for electron scattering from other tetrachoride molecules: XCl4 where X=C, Si, Ge.
Electron impact cross sections for H
2, HD and D
2
Authors: Prajapati D , Yadav H , Vinodkumar M , Vinodkumar P C
Published: June 2020

Synopsis

The demand for electron-impact cross sections has increased tremendously in recent years. There is, however, a special interest in such cross sections for hydrogen molecules and its isotopomers, HD and D
2. We have computed target properties & electron scattering cross sections for H
2, HD and D
2 and discuss different phenomena and their importance.
Ladder climbing in the spherical plasma
Authors: Geng P F , Tang R A , Zhang A X , Xue J K
Published: June 2020

Synopsis

We report the ladder climbing (LC) of the electron plasma density wave in the spherical plasma.
Chirped laser acceleration of electron in plasma channel
Authors: Hu Y N , Zhang X B , Zhang A X , Xue J K
Published: June 2020

Synopsis

Considering the asymmetry of chirped laser pulses, the dynamics of direct electron acceleration by chirped laser in a homogeneous cylindrical plasma channel is given.
60 years of attosecond physics at ICPEAC: from collisions to ultrashort pulses
Authors: Burgdörfer Joachim , Lemell Christoph , Tong Xiao-Min
Published: June 2020

The field of attosecond physics has seen an almost explosive growth since the early 2000’s and represents by now an increasing fraction of contributions to the bi-annual series of International Conferences of Photonic, Electronic, and Atomic Collisions (ICPEAC). The latter is anything but a coincidence as many of the underlying concepts of electronic and photonic dynamics are closely intertwined with atomic-scale collision processes. We illustrate this fruitful connection and its implications with the help of a few prototypical examples of current topical interest.
Particle emission from two-dimensional MoS2 induced by highly charged ion impact
Authors: Skopinski L , Ernst P , Herder M , Schleberger M
Published: June 2020

Synopsis

For many attractive applications of single layer MoS2 such as in optoelectronics e.g., the sample is supported by a substrate. Its importance for the modification through ion irradiation is here experimentally investigated by the analysis of sputtered particle of MoS2 on SiO2 and Au substrates under highly charged ion irradiation. The velocity distribution of the sputtered atoms is less affected by the substrate using highly charged projectiles than using slightly charged ones. Furthermore, we can show that potential sputtering causes additional emission of particles with lower kinetic energy.
Surface chemistry of colloidal surfactant-free gold nanoparticles generated by laser ablation
Authors: Lévy A , De Anda Villa M , Gaudin J , Amans D , Blanchet V , Boudjada F , Bozek J D , Grisenti R E , Lamour E , Laurens G , Macé S , Milosavljević A R , Nicolas C , Papagiannouli I , Patanen M , Prigent C , Robert E , Steydli S , Trassinelli M , Vernhet D
Published: June 2020

Synopsis

Surface chemistry of gold nanoparticles produced by laser ablation in liquids has been investigated using synchrotron radiation and the X-ray Photoelectron Spectroscopy technique. Thanks to the recorded core-level and valence spectra, combined with a detailed analysis based on Bayesian statistical methods, the oxide presence and its proportion on the nanoparticle surface have been determined.
Photoionization and photofragmentation of singly charged positive and negative Sc3N@C80 endohedral fullerene ions
Authors: Müller A , Martins M , Kilcoyne A L D , Phaneuf R A , Hellhund J , Borovik A , Holste K , Bari S , Buhr T , Klumpp S , Perry-Sassmannshausen A , Reinwardt S , Ricz S , Schubert K , Schippers S
Published: June 2020

Synopsis

Photoprocesses of the endohedral fullerene ions

Sc

3

N
@

C

80

+

and

Sc

3

N
@

C

80

−

in the gas phase have been experimentally investigated with emphasis on the specific effects of the encapsulated trimetallic nitride cluster Sc3N on the observed reaction yields. Clear evidence of photoexcitation near the Sc L edge is obtained with the dominating contributions visible in the one- and two-electron-removal channels. The experiments are accompanied by model calculations employing density functional theory (DFT).
Characterizing crystalline defects in single Xe nanoparticles from angular correlations of single-shot diffracted X-rays
Authors: Niozu A , Kumagai Y , Nishiyama T , Fukuzawa H , Motomura K , Bucher M , Ito Y , Takanashi T , Asa K , Sato Y , You D , Li Y , Ono T , Kukk E , Miron C , Neagu L , Callegari C , Fraia M Di , Rossi G , Galli D E , Pincelli T , Colombo A , Kameshima T , Joti Y , Hatsui T , Owada S , Katayama T , Togashi T , Tono K , Yabashi M , Matsuda K , Bostedt C , Nagaya K , Ueda K
Published: June 2020

Synopsis

We performed a wide-angle X-ray scattering experiment of single Xe nanoparticles using an X-ray free electron laser. We developed a novel analysis method that focuses on the angular correlation between plural Bragg spots in single-shot diffraction patterns. The angular correlations of the Bragg spots encode rich structural information and offer an evidence of twinning and stacking faults in Xe nanoparticles.
Plasmons in graphene traversed by relativistic electronic beam with arbitrary trajectories
Authors: Segui S , Gervasoni J L , Akbari K , Mišković Z , Arista N
Published: June 2020

Synopsis

In this work we study the energy loss of a beam of relativistic electrons impinging on a graphene sheet under oblique incidence. Using several models for the electric conductivity of graphene, we cover a wide range of frequencies of the energy loss spectrum, from the terahertz to the ultraviolet. To describe this spectrum, we consider the contribution of electronic excitations as well as that of transition radiation.
Ionization of pyrimidine molecule induced by proton
Authors: Quinto M A , Monti J M , Rivarola R D
Published: June 2020

Synopsis

In the present study will be investigated the ionization of isolated pyrimidine molecules induced by ions. The total and differential cross section have been computed with a quantum mechanical method within the continuum distorted wave-eikonal initial state (CDW-EIS) approximation. A comparison with the available data is presented.
Unexpected role of water on the fragmentation of hydrated biomolecule clusters
Authors: Wang E , Ren X , Dorn A
Published: June 2020

Synopsis

We study the ionization and fragmentation of tetrahydrofuran (THF) and hydrated THF clusters induced by low-energy (65 eV) electron-collision using an (e, 2e + ion) triple coincidence method. The momentum vectors and the kinetic energies for all three final-state charged particles are determined. The ionic fragments are identified from the measured ion time-of-flight spectra. The influence of the water environment on the biomolecule is investigated with the ion fragment correlated binding energy spectra and triple-differential cross sections as well as ab-initio dynamical calculations.
Charge exchange three- and four-body reactions in the presence of a laser field
Authors: Lévêque-Simon K , Hervieux P-A
Published: June 2020

Synopsis

Cross-sections computation of the formation of antihydrogen’ atoms or ions resulting from two consecutive collisions between positronium atoms and antiprotons is a central issue of GBAR’s experiment. In [2] cross-section calculations using a perturbative approach, have been undertaken, for the charge exchange three- and four-body reactions (1) and (2). In the present study, we investigate the influence of a laser field on these two reactions. We show that under special irradiation conditions, antihydrogen’ atom or ion formation cross-sections may be increased by the presence of the laser field.
Positronium formation in collisions between positrons and Rb, Cs atoms with screened Coulomb interaction
Authors: Ma J , Wang Y C , Li B , Wang Y B
Published: June 2020

Synopsis

Positronium formation processes in collisions between positrons and Rb, Cs atoms with Debye potentials are studied using the screening approximation model for screening parameters μ=0.00-0.25 at incident energy range 2-60 eV.
Dielectronic recombination rate coefficients for F-like nickel
Authors: Wang S X , Huang Z K , Wen W Q , Wang H B , Xu X , Schippers S , Khan N , Dou L J , Mahmood S , Mao L J , Ma X M , Li J , Tang M T , Yin D Y , Yuan Y J , Yang J C , Chen C Y , Shi Y L , Dong C Z , Ma X , Zhu L F
Published: June 2020

Synopsis

At the main cooler storage ring (CSRm) of IMP, Lanzhou, we have measured merged-beams rate coefficients for dielectronic recombination (DR) of F-like Ni in the energy range 0-160 eV which comprises all DR resonances associated with ΔN = 0 core excitations. We compare our results with calculations by the flexible atomic code (FAC). Good agreement is found between calculated and measured resonance parameters except for the low-energy 2s 2p6 (2S1/2)61 resonances. In addition, we have also derived plasma rate-coefficients from our data for applications in astrophysics.
Coincident mapping of e+ and e− from free-free pair production in a magnetic toroidal lepton spectrometer
Authors: Hagmann S , Hillenbrand P M , Litvinov Yu A , Spillmann U , Stöhlker Th
Published: June 2020

Synopsis

We discuss the electron-optical properties of a toroidal magnetic sector spectrometer and its suitablilty for electron-positron pair spectroscopy in relativistic ion-atom collisions in the future HESR storage ring at FAIR. With the simultaneous mapping of electrons and positrons and geometric invariants in the lepton trajectorties this instrument offers a very high efficiency for studies of vector momentum correlation in free-free pair production.
Status of CRYRING@ESR and preparations for first experiments
Authors: Lestinsky M , Andelkovic Z , Bai M , Bräuning-Demian A , Chetvertkova V , Fedotova S , Geithner O , Geithner W , Gorda O , Herfurth F , Kalinin A , Källberg A , Litvinov S , Menz E B , Mohr K , Sanchez R , Stöhlker T , Vorobjev G , Weinrich U
Published: June 2020

Synopsis

CRYRING was moved from Stockholm to Darmstadt, modernized and integrated into the GSI/FAIR beamline topology behind ESR. As CRYRING@ESR, it will receive and store heavy, highly charged ions from all species the present accelerator chain is capable of producing. An extensive research program on low-energy atomic collisions, spectroscopy and nuclear reactions was proposed. The facility is gradually completing commissioning, ion beams from the local injector branch have already been stored and prototype experiments performed. We present the machine status and highlight some planned experiments.
Towards background-free studies of capture reactions in a heavy-ion storage ring
Authors: Varga L , Blaum K , Davinson T , Glorius J , Jurado B , Langer C , Lederer-Woods C , Litvinov Yu A , Reifarth R , Slavkovská Z , Stöhlker T , Woods P J , Xing Y M
Published: June 2020

Synopsis

Stored and cooled highly-charged ions offer unprecedented capabilities for precision studies in realm of atomic-, nuclear-structure and astrophysics. In context of the latter, after the successful investigation of the cross section of 96Ru(p,γ) in 2009, in 2016 the first measurement of the 124Xe(p,γ)125Cs reaction was performed at the Experimental Storage Ring (ESR) at GSI.
Characterisation of ion bunches by a single-pass non-destructive charge counter
Authors: Kiffer M , Ringleb S , Stallkamp N , Kumar S , Arndt B , Vogel M , Quint W , Stöhlker Th
Published: June 2020

Synopsis

We present non-destructive single-pass ion bunch detection and characterisation by measuring the induced image charge in a detection electrode. The presented technique allows direct determination of ion kinetic energy, absolute ion number and spatial ion bunch length. We will show the results of corresponding measurements with bunches of low-energy highly charged ions and discuss the minimum detectable number of charges.
Bright single-cycle terahertz source based on gas cells irradiated by two-color laser pulses
Authors: Liseykina T.V. , Popruzhenko S.V.
Published: June 2020

We study the excitation of electron currents in a transparent cell of sub-millimeter size filled by an atomic gas and illuminated by an intense two-color femtosecond laser pulse. The pulse consists of a strong fundamental component and its second harmonic of low intensity, both circularly polarized. We show that for a sufficiently small 20μm-size interaction volume the plasma oscillation excited by asymmetric ionization is almost spatially homogeneous. This coherent dipole plasma oscillation results in a remarkably efficient conversion of the electron energy into that of radiation emitted in the terahertz frequency domain. Simultaneously, strong quasi-static electric fields of maximal strength Em
≃ 10MV/cm are shown to exist inside the plasma during several hundred femtoseconds after the ionizing two-color laser pulse has gone.
Dissociative electron attachment to SO2 near 7.5 eV resonance and axial-recoil approximation
Authors: Jana Irina , Naskar Sumit , Nandi Dhananjay
Published: June 2020

We present experimental results for dissociative electron attachment to sulfur dioxide near the 7.5 eV resonance. The dissociation channels leading to O−, S− and SO− ions formation have been investigated with a velocity map imaging technique. While the O− and SO− ions formed by dissociative electron attachment show angular distributions characteristic to a combination of A1+B2 symmetry, the S− ions show angular distributions resulting from changes in the orientation of the dissociating bond due to bending mode vibrations implying the failure of axial-recoil approximation.
Many-body-theory calculation of positronium scattering by atomic hydrogen
Authors: Swann A R
Published: June 2020

The recently developed many-body-theory approach for studying low-energy positronium-atom interactions is applied to calculate positronium scattering by atomic hydrogen. Calculations are carried out for the case where the two electrons are in a spin-triplet state. The elastic scattering phase shifts and cross sections are compared with existing coupled-channel, stochastic-variational, and Kohn-variational results, and excellent agreement is obtained.
Dissociative electron attachment to polyatomic molecules
Authors: Wang Xu-Dong , Gao Xiao-Fei , Li Hao , Wu Bin , Tian Shan X
Published: June 2020

Dissociative electron attachment (DEA) to molecule plays a key role in atmosphere, interstellar space and ionization damages of biological tissue. Experimental DEA studies of polyatomic molecules in gas phase provide the dynamics details that are the fundamentals to establish the physicochemical models of the electron-induced reactions in complicated environments. Since 2012, we successively set up two ion-velocity-map-imaging apparatuses, and accomplished a series of experimental studies of the DEA dynamics. Here is a brief review about our progresses on polyatomic molecules.
Negative ion relaxation and reactions in a cryogenic storage ring
Authors: Schmidt H T , Rosén S , Thomas R D , Stockett M H , Geppert W D , Larson Å , Löfgren P , Simonsson A , Källberg A , Reinhed P , Björkhage M , Blom M , Alexander J D , Najeeb P K , Ji M , Kono N , Anderson E K , Eklund G , Kristiansson M K , Hole O M , Hanstorp D , Hartman H , Barklem P S , Grumer J , Hansen K , Gatchell M , Cederquist H , Zettergren H
Published: June 2020

An overview of recent experimental results of studies of negative atomic and molecular ions in the Double ElectroStatic Ion-Ring ExpEriment, DESIREE is given. Metastable level lifetimes in atomic negative ions have been measured by time-dependent laser photodetachment. Rotational relaxation of diatomic anions is studied by near-threshold photodetachment. Spontaneous decays of small metal cluster anions by electron emission and fragmentation is studied with decay-channel specificity. Finally, mutual neutralisation of pairs of negative and positive ions has been investigated with initial and final state selectivity.
Broadband supercontinuum harmonics and isolated utrashort attosecond pulse generation by optimizing three-color laser fields
Authors: Yu H-Y , Jiao Z-H , Zhou X-X , Li P-C
Published: June 2020

Synopsis

We present an efficient scheme for the generation of broadband supercontinuum harmonics and isolated utrashort attosecond pulse by the optimized three-color laser fileds. The optimized laser pulse is synthesized by three one-color laser pulses with proper relative phases. The broadband supercontinuum harmonics are obtained by solving accurately the time-dependent Schrödinger equation using the time-dependent generalized pseudospectral method. Our scheme proposed produces a broadband supercontinuum spectrum with the photon energies near 0.3 keV. As a result, an isolated 17 as pulse can be obtained directly by superposing the supercontinuum harmonics.
Spin-orbit dynamics in atomic krypton observed through decay of autoionising states
Authors: Wragg J , Armstrong G , Clarke D , Ballance C , Brown A , van der Hart H
Published: June 2020

Synopsis

We study the spin-orbit interaction within excited states of krypton by extending R-Matrix with time-dependence theory to include spin-orbit effects. We study an attosecond pump-probe scheme where we produce an autoionising state with the probe pulse. We observe dynamics through the subsequent decay of the autoionising state, from which we find a time-dependent signal when spin-orbit interactions are included. We examine the effect of the relative polarisation of the pulses, enabling an interpretation of the dynamics in terms of the quantum number mℓ
of the core of the excited krypton atom.
Many-body calculations of two-photon, two color matrix elements for attosecond delays
Authors: Dahlström M , Ljungdahl A , Sörngård J , Vinbladh J , Lindroth E
Published: June 2020

Synopsis

Interferometric measurements based on the combination of extreme ultraviolet (XUV) attosecond pulse trains with weak infrared laser fields, have been successfully used to study time-resolved and recently angle-resolved photoemission in various atomic systems. These measurements rely on quantum interference between electron wavepackets created by absorption of XUV radiation, with further absorption or emission of laser photons. Here we present many-body calculations of the full two-photon process.
Signatures of Coriolis effects in molecular bichromatic circularly polarized high-order harmonic generation
Authors: Yuan K J , Bandrauk A D
Published: June 2020

Synopsis

Circularly polarized high-order harmonic generation in molecules by bicircular pulses has been studied. We describe the laser induced electron dynamics in a rotating frame. The Coriolis effects give rise to orthogonal polarization harmonics. It is found that harmonic property depends on pulse frequencies and helicities, molecular orbital symmetries, and electron localizations, illustrating the importance of the field-molecule symmetry. The feature is described by dynamical symmetry theory and time profile analysis of harmonics.
UV-pump/UV-probe spectroscopy of N2
Authors: Borràs V J , González-Vázquez J , Klinker M , Martín F
Published: June 2020

Synopsis

UV-pump / UV-probe photoelectron spectra of N2 are theoretically evaluated by solving the time-dependent Schrödinger equation in a basis of all-electron bound and continuum eigenstates provided by the XChem code.
Imaging an isolated water molecule with an attosecond electron wave packet
Authors: Liu X , Amini K , Steinle T , Sanchez A , Shaikh M , Belsa B , Steinmetzer J , Le A T , Moshammer R , Pfeifer T , Ullrich J , Lin C D , Gräfe S , Biegert J
Published: June 2020

Synopsis

We use laser-induced electron diffraction (LIED) to self-image the molecular structure of an isolated water molecular ion using its own retuning attosecond electron wave packet (EWP). Using LIED’s sub-femtosecond and picometre spatio-temporal resolution imaging capabilities, we observe the symmetric stretching of the O-H and H-H internuclear distances with increasing laser field strength.
Spatial distribution on high-order-harmonic generation of an H2
+ molecule in intense laser fields
Authors: Zhang J , Guo J , Liu X S
Published: June 2020

Synopsis

High-order-harmonic generation (HHG) for the H2
+ molecule in a 3-fs, 800-nm few-cycle Gaussian laser pulse is investigated by solving the time-dependent Schrödinger equation. The spatial distribution on HHG is demonstrated and the results present the recombination process of the electron with the two nuclei. And there is little possibility of the recombination of the electron with the nuclei around the origin z = 0 a.u. and equilibrium internuclear positions z = ±1.3 a.u.. The electron-nuclear wave packet and ionization probability are investigated to explain the physical mechanism.
Carrier-wave population transfer in semiconductors
Authors: Zuo R , Song X , Meier T , Yang W
Published: June 2020

Synopsis

We show that a novel carrier-wave population transfer, i.e., interband excitations are confined to an extremely short time window due to their coupling to the intraband motion, is responsible for the enhancement of the interband HHG and the anomalous carrier-envelope phase dependence observed in recent experiments on semiconductors. The results give the answers of how inter- and intraband dynamics are coupled together and why the interband polarization can dominate the HHG emission in many semiconductors which is a highly debated topic in the community.
Photoabsorption of atoms in a strong elliptical laser field
Authors: Gao X , Tong X-M
Published: June 2020

Synopsis

The photoabsorption of hydrogen atoms in a strong elliptical laser field was studied by solving the three-dimensional time-dependent Schrödinger equation. We found that the photoexcitation and ionization probabilities smoothly cross the ionization threshold and we can treate them in a unified way even in the strong elliptical laser field. Such findings may help us to understand how atomic structure affects the strong field ionization near the ionization threshold.
HILITE – A well-defined ion target for laser experiments
Authors: Stallkamp N , Ringleb S , Arndt B , Kiffer M , Kumar S , Paulus G G , Quint W , Stöhlker Th , Vogel M
Published: June 2020

Synopsis

We present a Penning-trap-based setup for the study of light-matter interactions in the high-power and/or high-intensity laser regime, such as multi-photon ionization and field ionization. The setup applies ion-cloud formation techniques to highly charged ions to the end of specific target preparation, as well as non-destructive detection techniques to identify and quantify the interaction educts and products.
Rescattering photoelectron spectroscopy of CO2 molecule with an analytical returning electron wavepacket
Authors: Okunishi M , Ito Y , Sharma V , Aktar S , Morishita T , Dnestryan A I , Tolstikhin O I , Lucchese R R , Ueda K
Published: June 2020

Synopsis

Angle-resolved photoelectron momentum distributions of rescattering electron generated by intense infrared laser pulses were measured for CO2 molecules. It is shown that the measured distributions along the outermost backward rescattering caustic are well reproduced by calculations based on a newly developed factorization formula with the analytical returning photoelectron wave packet.
Signatures of Light-Induced Potential Energy Surfaces in

H2+
Authors: Kübel M , Spanner M , Dube Z , Naumov A Yu , Vrakking M J J , Corkum P B , Villeneuve D M , Staudte A
Published: June 2020

Synopsis

Using theory and Cold Target Recoil Ion Momentum Spectroscopy we find signatures of light-induced molecular potential energy surfaces in the 3-dimensional proton momentum distributions of dissociating

H
2
+

.
Research on bremsstrahlung and Compton scattering in hot warm matters
Authors: Qi Y Y , Wang J G
Published: June 2020

Synopsis

Bremsstrahlung and Compton scattering are the important processes including the continuum electrons in the hot warm matters. The distribution of the continuum electrons is affected by the plasma screening, which will influence the cross sections of Bremsstrahlung and Compton scattering. In the present work we will investigate the plasma influence on these processes.
Solid State Root Preparation, Characterization and Electrical Properties of NiCuZnFe2O4 / Paraformaldehyde Nanocomposites
Authors: Raju P , Rajesham S , Shankar J , Anjaiah J , Neeraja Rani G
Published: June 2020

In this investigation, the structural and electrical properties of nanocomposites of NiCuZn ferrite (NCZ) and paraformaldehyde (PFD) synthesized by solid state mixing route are reported. Synthesized nanomaterials have been characterized by FT-IR and TGA techniques. FT-IR results confirm the presence of NCZ and PFD in the samples. The DC conductivity measurements have been investigated. The dielectric constant ε’ and dielectric loss ε” were found to increase as the PFD content increased to 50% and to decrease as the PFD content further increased. A dielectric cole-cole diagram can be obtained by plotting the dielectric loss ε” against the dielectric constant ε’. The cole cole diagram is generally used for studying the dielectric polarization characteristics by following the variation of dielectric loss ε” with dielectric constant ε’. From this work, it is possible to deduce interfacial polarization and dipolar polarization from dielectric cole-cole plots.
FTIR, Raman and XRD analysis of graphene oxide films prepared by modified Hummers method
Authors: Surekha G , Krishnaiah K Venkata , Ravi N , Padma Suvarna R
Published: June 2020

Graphene oxide (GO) is a promising material for energy storage device applications. Modified Hummers method (MHM) has been used to prepare GO films from graphite flakes by Sol-Gel method. With the aid of bridging agent dimethyldichlorosiline, structurally fine GO films were prepared. Fourier transform and infra-red (FTIR) spectrum of the GO thin film possesses absorption bands at 461, 594, 670, 803, 1020, 1243, 1457, 1544, 1627, 2850, 2926 and 3429 cm−1. A sharp OH− absorption band was revealed at 3429 cm−1. Two vibrational bands were noticed in the Raman spectrum for pure graphite flakes at 1578 and 2718 cm−1. However, for GO, five Raman vibrational bands were unveiled at 413, 1344, 1597, 2697 and 2945 cm−1. Among these bands, the mode at 1344 cm−1 was assigned to D-band and 1597 cm−1 was assigned to G-band. Compared to D-band, G-band was dominated for the GO films. Several times of centrifugation and ultra-sonication process have aided to obtain more intensity of G-band. In addition, 2D and D + G bands were also revealed in the GO films. X-ray diffraction (XRD) analysis was confirmed that a sharp peak at 10.64 degrees leads to the formation of GO thin film.
Influence of active layer thickness on the cut-off frequency of a-IGZO thin film transistors
Authors: Raj Roshna B , Nair Shiny , Tripathi Ashutosh , Mukundan T , Shahana T K
Published: June 2020

Design optimizations like channel length and gate/contact overlap length scaling are generally used for cut-off frequency (fT
) enhancement of thin film transistors (TFT). But channel length scaling leads to mobility degradation due to contact resistance (RC
). RC
in TFTs is directly proportional to the transfer length (LT
), and is inversely proportional to the overlap length (LOV
). LT
depends upon the metal/semiconductor interfacial resistivity, the vertical bulk resistance and the semiconductor sheet resistance. For the same interfacial contact properties, active layer thickness (Ta
) scaling can be effectively utilized for lowering the vertical bulk resistance thereby lowering LT
and enhancing fT
. To study the effect of thickness scaling on the bandwidth of TFT based amplifiers, a-IGZO thin film transistor of effective channel thickness of 70nm are first fabricated and characterized. Density of states model of this TFT is extracted and numerical simulations are used to study the influence of active layer thickness scaling. By varying the channel lengths from 10μm to 100μm, transfer line method of contact resistance estimation, is used to extract LT
and RC
of devices. As the active layer thickness is varied from 70μm to 30μm it is found that LT
decreases from 1μm to 60 nm, due to lower vertical bulk resistance. This results in a lower RC
and higher μeff, facilitating further scaling of LOV
, leading to enhanced fT
of the device.
Structural, mechanical and electrical properties of NiO - GDC20 composite anodes for low or intermediate temperature solid oxide fuel cells
Authors: Reddy M Narsimha , Vijaya Bhaskar Rao P , Bhoga S S , Bansod Mahesh , babu V Sreehari
Published: June 2020

Nano Composites NiO and 20 mol% gadolinium doped ceria (GDC20) were synthesized as X (NiO) +1-X (Ce0.8 Gd0.2 O2-δ) where (X = 40& 45 wt. %) for intermediate or low temperature operating solid oxide fuel cells (SOFC). For composite anode materials, NiO and GDC20 nano powders were mechanically mixed and calcined from 600 °C to 750 °C. Samples were pelletized and sintered at 1300°C. Systematic study of structure, purity, phase and structural parameters of anode samples were carried out by XRD and SEM. Mechanical strength of anode composites were estimated by Vickers micro-hardness and observed that microhardness of composites are varying from 9.37 GPa to 11.25GPa. Electrical properties D.C conductivity and A.C conductivity of anode composites were computed using four probe method and impedance analyser respectively. The A.C conductivity and their activation energies of the anode samples (compositions X = 40 & 45 wt. %) were computed from RT to 500°C with the impedance spectrosopy data and the conductivities are found 2.95 x 10−3 S/cm and 7.53 x 10−2 S/cm respectively at 500°C (frequency 1.33 MHz). The activation energies of A.C conductivity have observed that decrease with increase in frequencies.
XRD Investigation on Heat Treatment of High Chrome White Cast Irons
Authors: Ngqase M. , Pan X.
Published: June 2020

The properties of hypoeutectic iron of HCWCI containing 25 wt. %Cr-2.5 wt. %C were investigated after destabilisation heat treatments, cooling (slow and fast cooling) to ambient temperatures, their influence on the structure and hardness was investigated using X-ray diffraction (XRD), element distribution analysis and hardness tests. The experimental results show that appropriate heat treatments contribute to a significant improvement on the mechanical properties of selected alloy of HCWCI. The results are discussed in terms of the change in austenite phase at the different destabilisation heat treatment temperatures.
Study on ultrasound velocities and elastic properties of sodium diboro-vanadate glasses
Authors: Harikamalasree N , Reddy Sivasankara , Narayana Reddy C.
Published: June 2020

Glasses with general formula xNa2O-15V2O5-(85-x)B2O3 where x is varied from 5 to 50 mol% in steps of 5 mol%, are fabricated using melt quenching technique. Ultrasound velocities, elastic moduli and Poisson’s ratio exhibit composition dependent trends. Both ultrasound velocities and elastic moduli increases with the addition of Na2O mol% whereas Poisson’s ratio decreases. The introduction of V2O5 results in the formation of diboro-vanadate units similar to that of a diborate. Formation of these diboro-vanadate units leads to a monotonic increase in both sound velocities and elastic moduli.
A Low-Cost Electroencephalography (EEG) Instrumentation for Epileptic Seizure Detection
Authors: Bera Tushar Kanti , Choudhary Sunil , Maiti Toushik , Prasad Barnwal Suraj
Published: June 2020

Noninvasive detection of epileptic seizures can help the patients to save themselves from sudden fall and assist the doctors to study the disease and treat the patient. Generally, an EEG based epileptic seizure detection system consists of EEG sensors, electronic instrumentation and a signal processing algorithm. In this paper, an EEG acquisition system (EAS) has been developed with a multi-stage amplifier and filter blocks. The instrumentation is studied, tested and evaluated with periodic signals generated with a function generator as well as the EEG-like signals simulated by virtual instrumentation (VI) developed with NI MyDAQ controlled by a Lab VIEW. The noise response of the instrumentation developed has been studied with SNR analysis. Results, obtained from the circuit simulation and experimentation conducted with EEG-like waveforms, show that the developed EAS is suitable to process the EEG signals and suitable for epileptic seizures detection systems.