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The advent of attosecond spectroscopy, in particular high harmonic generation spectroscopy, has led to advances in following electronic dynamics in atoms and molecules on their natural timescale. The recent discovery of the high harmonic generation in bulk solids [1-8] has opened the door for applying HHG spectroscopy for ultrafast investigations of the electronic dynamics in the condensed phase,...
In experiments with the use of laser fluorescence spectroscopy (LFS) in vivo both for endogenous porphyrin at occlusive ischemia and for exogenous phthalocyanine of aluminum at induced inflammatory processes the enhanced autofluorescence in the red waveband was detected. It means that the LFS in vivo can be an effective tool for the registration of both the ischemic hypoxia and inflammatory processes...
Strong field ionization of atoms and molecules is often viewed as electron tunneling through the barrier created by the laser field and core potential. In multielectron systems new tunneling channels driven by electron correlations may arise leading to complex attosecond dynamics of electron rearrangement [1]. High harmonic spectroscopy [2] provides an opportunity to record these complex dynamics...
Even moderate laser fields with intensities of about 1013 W/cm2, standard in many ultrafast experiments, suppress the potential barrier for ionization for all excited states in most atoms and molecules. By means of angle resolved photoelectron spectra, we have shown [1] that in this regime the formation of stable “laser-dressed” atoms, the so-called Kramers-Henneberger (KH) atoms [2], plays a crucial...
One of the key goals of attosecond spectroscopy is to time resolve the multielectron rearrangement that takes place when an electron is removed from a molecule using a short laser pulse. While XUV pulses address core electrons, infrared pulses address valence electrons, and can be used to excite electron dynamics in the valence shells via a strong field ionization process [1].
We present [1] a way to control and shape the polarization of attosecond pulses generated by HHG by using the combination of the fundamental radiation and its second harmonic, both linearly polarized, in perpendicular geometry. By extending the multi-electron analysis done in the C02 molecule in previous works [2] to treat the two-color laser fields, we explore the rich possibilities that this control...
We recently developed a new theoretical tool, analytical R-matrix (ARM) [1], adopting the R-matrix approach developed in [2] for collision processes and nuclear resonance reactions, to study strong field ionisation processes in circularly polarised fields. Our method can consistenly include the effects of arbitrary, long-range potentials on the ionisation process and thus focus on non-adiabatic dynamics...
The advent of new XUV light sources such as free electron lasers, and the development of high harmonic emission both as a light source and as a direct probe, coupled with advances in detector technology and the laser alignment of molecules, has opened up the possibility of observation, initiation and control of the fastest molecular processes. Exposing aligned molecules to these short, femtosecond...
We implement a novel parametric waveform synthesizer based on three carrier-envelope-phase-locked femtosecond pulses with tunable commensurate/-incommensurate carrier-frequencies. Directional electron emission asymmetry in such light-fields is shown to cause the generation of tunable Brunel-type sideband radiation.
Grid and e-science infrastructure interoperability is an increasing demand for Grid applications but interoperability based on common open standards adopted by Grid middle-wares are only starting to emerge on Grid infrastructures and are not broadly provided today. In earlier work we have shown how open standards can be improved by lessons learned from cross-Grid applications that require access to...
In this paper attosecond measurement relies on a phase "gate". The phase of attosecond pulses is easily manipulated because attosecond pulses arise in an interferometric process - the interferometer formed by an electron being removed by the atom, propagating in the laser field and re-colliding with the parent ion where the interference occurs. Slightly modifying (gating) the phase of the...
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