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We report experiments on the direct observation of O2 formation from CO2 in strong laser fields. Our simulations and pump-probe measurements suggest that CO2 undergos bending motion during strong-field ionization which supports the O2 formation.

Recent breakthroughs in ultrafast photonics in the mid-IR help understand complex interactions of high-intensity mid-IR field waveforms with matter, offer new approaches for x-ray generation, enable mid-IR laser filamentation in the atmosphere, facilitate lasing in filaments, give rise to unique regimes of laser-matter interactions, and reveal unexpected properties of materials in the mid-IR range.

We experimentally observed high-lying (n>238) Rydberg states which are formed through recapture of electrons after strong field interaction in atoms and small molecules using electron and ion coincidence detection. The high-lying Rydberg states are identified through weak DC field-induced ionization.

We report experimental observation of "slow" fragmentation from ethylene molecules on nanosecond or even microsecond timescale after their interaction with femtosecond laser pulses. Our results indicate that such fragmentation process originates from meta-stable high-lying vibrational states of ethylene ions.

We have studied the double ionization of Helium induced by intense (up to 1×1016 W/cm2) ultra-short (4-4.5 fs) circularly polarized laser pulses with a stabilized CEO phase.

Single- and double-ionization of neon with orthogonally polarized two-color (OTC) laser fields is investigated using the COLTRIMS method. We study the influence of the long range Coulomb potential of the parent ion on the final momentum distribution of electrons emitted during single ionization. Furthermore, we investigate nonsequential double ionization in OTC fields and demonstrate that the electron-electron correlation is highly sensitive to the sub-cycle field shape of the OTC pulses, in agreement with recent theoretical predictions., 28th International Conference on Photonic, Electronic and Atomic Collisions, ICPEAC 2013, July 24-30, 2013, Lanzhou

Control over various fragmentation reactions of a series of polyatomic molecules (acetylene, ethylene, 1,3-butadiene) by the optical waveform of intense few-cycle laser pulses is demonstrated experimentally. We show both experimentally and theoretically that the responsible mechanism is inelastic ionization from inner-valence molecular orbitals by recolliding electron wave packets.

We show experimentally and theoretically, using acetylene as an example, that the strong preponderance of ionization from specific molecular orbitals to the alignment of the molecular axis with respect to the laser polarization direction allows implementing a method for controlling fragmentation reactions of polyatomic molecules.

We experimentally investigate and control the influence of the Coulomb binding potential on momentum spectra of electron wave packets created by strong-field ionization in a two-color laser field.

We have studied the double ionization of Helium with ultra short intense circularly polarized light pulses at intensities up to 1.5×1016 W/cm2 and pulse durations as short as 5.5 fs.

We report on the observation of an ionization-fragmentation process that puts a polyatomic molecule into a very high charge state of +12 and beyond at laser intensities as low as a few 1014 W/cm2 and subsequently leads to complete molecular decomposition. Our surprising experimental evidence shows that all of the molecule's protons are ejected with high kinetic energies, which is inconsistent with the explanation based on dynamic charge localization used in [1] to explain the proton energy. Furthermore, the energies of all the protons are very similar, which indicates that at the instance of decomposition the protons interact with the same molecular charge state, suggesting an all-at-once (concerted) fragmentation scenario.

We experimentally demonstrate control over interference structures of electron wave packets created and driven by a strong two-color laser field. Interferences of wave packets that are created within the same laser cycle and those that originate from different cycles are identified and controlled by the laser field's shape.