A5014120168- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
- Mass Spectrometry Techniques and Applications
- Renal cell carcinoma treatment
- Ferroptosis and cancer prognosis
- Nuclear physics research studies
- Ion-surface interactions and analysis
- Spectroscopy and Quantum Chemical Studies
- Cold Atom Physics and Bose-Einstein Condensates
- Analytical chemistry methods development
- X-ray Spectroscopy and Fluorescence Analysis
- Particle accelerators and beam dynamics
- Laser-induced spectroscopy and plasma
- Quantum, superfluid, helium dynamics
- Laser-Plasma Interactions and Diagnostics
- Mercury impact and mitigation studies
- Electron and X-Ray Spectroscopy Techniques
- Nuclear Physics and Applications
- Plasma Diagnostics and Applications
- Photochemistry and Electron Transfer Studies
- Photoreceptor and optogenetics research
- Atomic and Subatomic Physics Research
- Molecular Junctions and Nanostructures
- Quantum optics and atomic interactions
Goethe University Frankfurt
2015-2024
Universidade Federal de Santa Maria
2010-2024
Goethe Institute
2024
Icahn School of Medicine at Mount Sinai
2023-2024
Universidade Federal do Rio de Janeiro
2022
Klinik und Poliklinik für Nuklearmedizin
1995-2021
Universidade Tecnológica Federal do Paraná
2021
Universidade Federal do Rio Grande do Sul
2015-2020
Philipps University of Marburg
1996-2019
Rede de Química e Tecnologia
2014
Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions electrons resulting from atomic or molecular fragmentation. In unique combination, large solid angles close 4π superior resolutions around few per cent an unit (a.u.) are typically reached in state-of-the art machines, so-called reaction-microscopes. Evolving recoil-ion cold target (COLTRIMS), reaction-microscopes—the `bubble chambers physics'—mark...
The wave nature of particles is rarely observed, in part because their very short de Broglie wavelengths most situations. However, even with close to the size surroundings, couple environment (for example, by gravity, Coulomb interaction, or thermal radiation). These couplings shift phases, often an uncontrolled way, and resulting decoherence, loss phase integrity, thought be a main cause transition from quantum classical behavior. How much interaction needed induce this transition? Here we...
H 2 , the smallest and most abundant molecule in universe, has a perfectly symmetric ground state. What does it take to break this symmetry? We found that inversion symmetry can be broken by absorption of linearly polarized photon, which itself symmetry. In particular, emission photoelectron with subsequent dissociation remaining + fragment shows no respect ionic neutral atomic fragments. This lack results from entanglement between antisymmetric states is caused autoionization. The...
Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether core vacancy created a homonuclear diatomic molecule by absorption single x-ray photon is localized on one atom or over both. We been able to clarify this with an experiment that uses Auger electron angular emission patterns from nitrogen after inner-shell ionization as ultrafast probe hole localization. The experiment, along accompanying...
We coincidently measure the molecular frame photoelectron angular distribution and ion sum-momentum of single double ionization CO molecules by using circularly elliptically polarized femtosecond laser pulses, respectively. The orientation dependent rates for various kinetic energy releases allow us to individually identify ionizations multiple orbitals, ranging from highest occupied next two lower-lying orbitals channels observed in our experiments. Not only emission a electron, but also...
Fragmentation of highly charged molecular ions or clusters consisting more than two atoms can proceed in a one step synchronous manner where all bonds break simultaneously sequentially by emitting ion after the other. We separated these decay channels for fragmentation ${\mathrm{CO}}_{2}^{3+}$ measuring momenta ionic fragments. show that total energy deposited is control parameter which switches between three distinct pathways: sequential emission an ${\mathrm{O}}^{+}$ leaves rotating...
We report on nonsequential double ionization of Ar by a laser pulse consisting two counterrotating circularly polarized fields (390 and 780 nm). The double-ionization probability depends strongly the relative intensity shows kneelike structure as function intensity. conclude that is driven beam nearly monoenergetic recolliding electrons, which can be controlled in energy field parameters. electron momentum distributions show well second escapes from an intermediate excited state Ar^{+}.
We have measured the angular distributions of 1s photoelectrons excited by circularly and linearly polarized light from fixed-in-space CO N2 molecules, in vicinity their shape resonances. A strong circular dichroism, i.e., a dependence on sense rotation polarization vector photons, is found for both molecules. State-of-the-art one-electron multiple scattering partially correlated random phase approximation calculations are good agreement with many, but not all, aspects experimental data.
We have studied electron emission from the ${\mathrm{H}}_{2}^{+}$ ion by a circularly polarized laser pulse (800 nm, $6\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$). The momentum distribution in body fixed frame of molecule is experimentally obtained coincident detection electrons and protons. data are compared to solution time-dependent Schr\"odinger equation two dimensions. find radial angular distributions which at odds with quasistatic enhanced...
Many efforts have been made in order to reduce the amount of reagents and waste produced analytical laboratories. However, suitable digestion efficiency must be considered, depending on sample preparation procedure, incomplete can result severe matrix effects during analysis by spectrometric techniques such as ICP OES ICP-MS. In present work a procedure based use H2O2 was developed minimize consumption HNO3 without decreasing digestion. Although has used combined with for digestion, its role...
During the past 15 years a novel decay mechanism of excited atoms has been discovered and investigated. This so-called interatomic Coulombic (ICD) involves chemical environment electronically atom: excitation energy is transferred (in many cases over long distances) to neighbor initially particle usually ionizing that neighbor. It turned out ICD very common route in nature as it occurs across van der Waals hydrogen bonds. The time evolution predicted be highly complex, its efficiency...
The spin polarization of electrons from multiphoton ionization Xe by 395 nm circularly polarized laser pulses at 6×10^{13} W/cm^{2} has been measured. At this photon energy 3.14 eV the above-threshold peaks connected to Xe^{+} ions in ground state (J=3/2, potential I_{p}=12.1 eV) and first excited (J=1/2, I_{p}=13.4 are clearly separated electron distribution. These two combs show opposite polarizations. magnitude is a factor 2 higher for J=1/2 than J=3/2 final ionic state. In turn, data...
We report on the non-adiabatic offset of initial electron momentum distribution in plane polarization upon single ionization argon by strong field tunneling and show how to experimentally control degree non-adiabaticity. Two-color counter- co-rotating fields (390 780 nm) are compared that strongly depends temporal evolution laser electric field. introduce a simple method for direct access using two-color fields. Further, single-color circularly polarized at nm we radius observed donut-like...
Even though ion/atom-collision is a mature field of atomic physics great discrepancies between experiment and theoretical calculations are still common. Here we present experimental results with highest momentum resolution on single ionization helium induced by 1\,MeV protons compare these to different calculations. The overall agreement strikingly good already the first Born approximation yields theory experiment. This has been expected since several decades, but so far not accomplished....
Strong-field ionization of atoms by circularly polarized femtosecond laser pulses produces a donut-shaped electron momentum distribution. Within the dipole approximation this distribution is symmetric with respect to polarization plane. The magnetic component light field known shift forward. Here, we show that nondipole effect not only in strong-field ionization. We find an electric arises due position dependence and which can be understood analogy Doppler effect. This manifests as increase...
Ultrashort x-ray pulses from free-electron lasers can efficiently charge up and trigger the full fragmentation of molecules. By coincident detection to five ions resulting rapid Coulomb explosion highly charged iodomethane, we show that three-dimensional equilibrium geometry this prototypical polyatomic system be determined measured ion momenta with help a buildup model. Supported by simulations how would reflect specific changes in molecular bond lengths angles, demonstrate...
We have used complete correlated momentum mapping of the photoelectron and heavy ion products from dissociation di-cation acetylene, induced by photoionizing carbon K shell one atoms, to map out angular correlation between electron axis target molecule. The (quasi-) symmetric decay is found proceed through both acetylene vinylidene configurations. By using strongly peaked emission "start a clock," an upper limit 60 fs placed on isomerization time configuration.
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.