A5035163742- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy and Quantum Chemical Studies
- Advanced Fiber Laser Technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum optics and atomic interactions
- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser Design and Applications
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Ion-surface interactions and analysis
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Terahertz technology and applications
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Laser Applications
- Advanced Electron Microscopy Techniques and Applications
- Photonic and Optical Devices
- Diamond and Carbon-based Materials Research
Australian National University
2016-2025
Goethe University Frankfurt
2007-2018
Georgia State University
2018
Indian Institute of Technology Mandi
2016
Saratov State University
2016
Max Planck Society
2002-2011
Curtin University
2010
University of California, Santa Barbara
2010
Murdoch University
2007
Institute of Spectroscopy
2006
Time and place of electron exit Until about a decade ago, laser-induced ionization was considered instantaneous. Since then, applications attosecond laser pulses have shown multiple subtle complex factors that influence the precise timing ejection from atoms surfaces. Vos et al. measured corresponding dynamics dissociative photoionization in diatomic molecule, carbon monoxide. By imaging charged fragments, could be correlated with specific spatial portion molecule which wave packet emerged....
The substantial progress that has occurred during the 1990s in field of electron-atom-collision theory is discussed. We show how a solution small-model three-body problem, using convergent close-coupling method, led to numerous applications involving real atomic collision systems. Consequently many fundamental electron-atom processes are considered as `solved', and accurate data interest science industry have become available. However, we suggest present only just seen birth modern theory....
We analyze the time delay between emission of photoelectrons from outer valence ns and np subshells in noble gas atoms following absorption an attosecond extreme ultraviolet pulse. Various processes such as elastic scattering photoelectron on parent ion many-electron correlation affect apparent "time zero" when leaves atom. This qualitatively explains photoemission 2s 2p Ne determined experimentally by streaking [Science 328, 1658 (2010)]. However, with our extensive numerical modeling, we...
Time delays of electrons emitted from an isotropic initial state with the absorption a single photon and leaving behind ion are angle independent. Using interferometric method involving XUV attosecond pulse trains IR-probe field in combination detection scheme, which allows for full three-dimensional momentum resolution, we show that measured time between liberated $1{s}^{2}$ spherically symmetric ground helium depend on emission direction relative to common linear polarization axis ionizing...
We present experimental measurements and theoretical calculations of photoionization time delays from the $3s$ $3p$ shells in Ar photon energy range 32--42 eV. The are performed by interferometry using attosecond pulse trains infrared laser used for their generation. approach includes intershell correlation effects between within framework random-phase approximation with exchange. connection single-photon ionization two-color two-photon process measurement is established recently developed...
We use the nonrelativistic random-phase approximation with exchange to perform calculations of valence-shell photoionization Ne, Ar, Kr, and Xe from their respective thresholds photon energy 200 eV. The derivative complex phase matrix elements is converted photoelectron group delay that can be measured in attosecond streaking or two-photon sideband interference experiments. Comparison reported time-delay measurements Ne Ar at a few selected energies made. Systematic mapping time across wide...
Photoionization by an eXtreme UltraViolet (XUV) attosecond pulse train (APT) in the presence of infrared (RABBITT method) conveys information about atomic photoionization delay. By taking difference spectral delays between pairs rare gases (Ar,He), (Kr,He) and (Ne,He) it is possible to eliminate each case larger group delay ('attochirp') associated with APT itself obtain Ar, Kr Ne Wigner referenced model calculations He In this work we measure how vary as a function XUV photon energy but...
We determine relative photoemission time delays between valence electrons in different noble gas atoms (Ar, Ne and He) an energy range 31 37 eV. The are ionized by attosecond pulse train synchronized with infrared laser field the measured using interferometric technique. compare our results calculations random phase approximation exchange multi-configurational Hartree–Fock. also investigate influence of ionization angular channels.
Abstract For over a century since the Nobel prize winning work by Einstein (1905 Ann. Phys. 17 132), atomic photoionization was thought to be an instantaneous process. Recent experimental advances in ultrashort laser pulse generation has allowed resolve this process time. The concept of time delay introduced Wigner (1955 Rev. 98 145–7) particle scattering appears central resolution photoionization. In review, we examine fundamental concepts time-resolved ionization processes. We will follow...
Recoil-ion momentum distributions for two-photon double ionization of He and Ne (variant Planck's over omega=44 eV) have been recorded with a reaction microscope at FLASH (the free-electron laser Hamburg) an intensity approximately 1 x 10(14) W/cm2 exploring the dynamics two fundamental two-photon-two-electron pathways, namely, sequential direct (or nonsequential) absorption photons. We find strong differences in recoil-ion patterns mechanisms pointing to significantly different two-electron...
Pulses of x-ray light that last mere attoseconds are essential to capturing fundamental processes in nature, such as the motion electrons and their role chemical bonding. New experiments generate and, for first time, characterize attosecond pulses soft-x-ray portion spectrum.
Attosecond angular streaking, also known as the "attoclock", employs a short elliptically polarized laser pulse to tunnel ionize an electron from atom or molecule and put time stamp on this process by deflecting photoelectron in spatial direction. This deflection can be used evaluate tunneling spends under classically inaccessible barrier determine whether is finite. In review, we examine latest experimental theoretical findings present comprehensive set of evidence supporting zero scenario.
The convergent close-coupling (CCC) formalism is employed to calculate the fully resolved triply differential cross section (TDCS) for helium double photoionization. This first ab initio calculation of kind where all three gauges electromagnetic interaction produce TDCS within a few per cent each other. Comparison made with experimental data in range photon energies 10 - 53 eV above threshold, both equal and unequal energy sharing. present calculations agree very well, shape available...
We perform a systematic study of photoionization with excitation and double ${\mathrm{H}}^{\ensuremath{-}},$ He, ${\mathrm{Li}}^{+}$ using the convergent close-coupling formalism. The present calculations cover photon energy range from double-ionization threshold to 10 keV where results go over continuously nonrelativistic limit infinite energy. By consideration scaling properties, tested by application ${\mathrm{O}}^{6+},$ accurate for arbitrarily high n may be obtained all heliumlike targets.
We have measured fully differential cross sections for photo double ionization of helium 450 eV above the threshold. found an extremely asymmetric energy sharing between photoelectrons and angular asymmetry parameter beta approximately 2 0 fast slow electrons, respectively. The electron distributions show a dominance shakeoff electrons clear evidence inelastic electron-electron scattering at 30 eV. data are in excellent agreement with convergent close-coupling calculations.
We perform time-dependent calculations of strong-field ionization He by elliptically polarized light in configuration recent attoclock measurements Boge et al. [Phys. Rev. Lett. 111, 103003 (2013)]. By solving a three-dimensional Schr\"odinger equation, we obtain the angular offset ${\ensuremath{\theta}}_{m}$ maximum photoelectron momentum distribution polarization plane relative to position predicted approximation. This is used extract tunneling time. Our clearly support set experimental...
We report photoelectron energy spectra, momentum, and angular distributions for the strong-field single ionization of lithium by 30-fs laser pulses. For peak intensities between ${10}^{11}$ ${10}^{14}$ W/cm${}^{2}$ at a central wavelength 785 nm, classical over-the-barrier intensity was reached well inside multiphoton regime. The complete vector momenta fragments were recorded reaction microscope with magneto-optically trapped target (MOTREMI). On theoretical side, time-dependent...
We study laser-sub-cycle control over electron trajectories concomitantly in space and time using orthogonally polarized two-color laser fields. compare experimental photoelectron spectra of neon recorded by coincidence momentum imaging with obtained semiclassical numerical solutions the time-dependent Schr\"odinger equation. find that a resolution quarter optical cycle can be achieved. It is shown depending on their sub-cycle birth photoelectrons are affected differently ion's Coulomb field.
The effects of confinement resonances on photoelectron group delay (Wigner time delay) following ionization an atom encapsulated inside a ${\text{C}}_{60}$ cage have been studied theoretically using both relativistic and nonrelativistic random phase approximations. results indicate clearly the resonant character oscillations in $4d$ shell Xe@${\text{C}}_{60}$ present most direct manifestation Wigner delay. These were missed previous theoretical investigation Ar@${\text{C}}_{60}$ [Phys. Rev....
We demonstrate a clear similarity between attoclock offset angles and Rutherford scattering taking the Keldysh tunnelling width as impact parameter vector potential of driving pulse asymptotic velocity. This simple model is tested against solution time-dependent Schr\"odinger equation using hydrogenic screened (Yukawa) potentials equal binding energy. observe smooth transition from to 'hard-zero' intensity dependence angle with variation Yukawa screening parameter. Additionally we make...