21 research outputs found
Laser-sub-cycle two-dimensional electron momentum mapping using orthogonal two-color fields
The two-dimensional sub-cycle-time to electron momentum mapping provided by
orthogonal two-color laser fields is applied to photoelectron spectroscopy.
Using neon as the example we gain experimental access to the dynamics of
emitted electron wave packets in electron momenta spectra measured by
coincidence momentum imaging. We demonstrate the opportunities provided by this
time-to-momentum mapping by investigating the influence of the parent ion on
the emitted electrons on laser-sub-cycle times. It is found that depending on
their sub-cycle birth time the trajectories of photoelectrons are affected
differently by the ion's Coulomb field
Role of proton dynamics in efficient photoionization of hydrocarbon molecules
We experimentally investigate the ionizationmechanism behind the formation of remarkably high charge states
observed in the laser-pulse-induced fragmentation of different hydrocarbon molecules by Roither et al. [Phys.
Rev. Lett. 106, 163001 (2011)], who suggested enhanced ionization occurring at multiple C-H bonds as the
underlying ionization mechanism. Using multiparticle coincidence momentum imaging we measure the yield of
multiply charged fragmenting ethylene and acetylene molecules at several intensities and pulse durations ranging
from the few-cycle regime to 25 fs. We observe, at constant intensity, a strong increase of the proton energy
with increasing laser pulse duration. It is shown that this is caused by a strong increase in the yield of highly
charged parent molecular ions with pulse duration. Based on experimental evidence we explain this increase by
the necessary population of precursor states in the parent ion that feature fast C-H stretch dynamics to the critical
internuclear distance, where efficient ionization via enhanced ionization takes place. For increasing pulse duration
these precursor ionic states are more efficiently populated, which leads in turn to a higher enhanced-ionization
probability for longer pulses. Our work provides experimental evidence for the existence of a multiple-bond
version of enhanced ionization in polyatomic molecule
Role of proton dynamics in efficient photoionization of hydrocarbon molecules
We experimentally investigate the ionizationmechanism behind the formation of remarkably high charge states
observed in the laser-pulse-induced fragmentation of different hydrocarbon molecules by Roither et al. [Phys.
Rev. Lett. 106, 163001 (2011)], who suggested enhanced ionization occurring at multiple C-H bonds as the
underlying ionization mechanism. Using multiparticle coincidence momentum imaging we measure the yield of
multiply charged fragmenting ethylene and acetylene molecules at several intensities and pulse durations ranging
from the few-cycle regime to 25 fs. We observe, at constant intensity, a strong increase of the proton energy
with increasing laser pulse duration. It is shown that this is caused by a strong increase in the yield of highly
charged parent molecular ions with pulse duration. Based on experimental evidence we explain this increase by
the necessary population of precursor states in the parent ion that feature fast C-H stretch dynamics to the critical
internuclear distance, where efficient ionization via enhanced ionization takes place. For increasing pulse duration
these precursor ionic states are more efficiently populated, which leads in turn to a higher enhanced-ionization
probability for longer pulses. Our work provides experimental evidence for the existence of a multiple-bond
version of enhanced ionization in polyatomic molecule
Spatial control of electronic wave packets with attosecond precision
Atomic single- and double- ionization using orthogonally polarized two-color laser fields was investigated via COLTRILMS technique. We prove that the electronic wave packets can be spatially controlled with attosecond precision.Peer reviewed: YesNRC publication: Ye
Attosecond probe of valence electron wavepackets by sub-cycle sculpted laser fields
We experimentally and theoretically demonstrate a self-referenced wave-function retrieval of a valence-electron wave packet during its creation by strong-field ionization with a sculpted laser field. Key is the control over interferences arising at different time scales. Our work shows that the measurement of subcycle electron wave-packet interference patterns can serve as a tool to retrieve the structure and dynamics of the valence-electron cloud in atoms on a sub-10-as time scale.Fil: Xie, Xinhua. Vienna University of Technology; AustriaFil: Roither, Stefan. Vienna University of Technology; AustriaFil: Kartashov, Daniil. Vienna University of Technology; AustriaFil: Persson, Emil. Vienna University of Technology; AustriaFil: Arbo, Diego. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Vienna University of Technology; AustriaFil: Zhang, Li. Vienna University of Technology; AustriaFil: Gräfe, Stefanie. Vienna University of Technology; AustriaFil: Schöffler, Markus S.. Vienna University of Technology; AustriaFil: Burgdörfer, Joachim. Vienna University of Technology; AustriaFil: Baltuska, Andrius. Vienna University of Technology; AustriaFil: Kitzler, Markus. Vienna University of Technology; Austri