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Since its first observation almost three decades ago high-order harmonic generation (HHG) in gases became a reliable source of extreme ultraviolet (XUV) pulses, which gave the possibility to study electronic processes on their natural timescale [1, 2]. While the main building blocks of the experimental setups for gas HHG are the same in almost all cases, the focusing or medium geometry varies from...
We demonstrate a tool for quantitative measurements in the linear and non-linear extreme ultraviolet (XUV) spectral region measuring spatially resolved atomic ionization products at the focus of an XUV beam [1, 2]. The ionizing radiation is a comb of the 11th-15th harmonics of a Ti:Sapphire femtosecond laser beam produced in a Xenon gas jet. The spatial ion distribution at the focus of the harmonics...
Nonlinear photoionization with energetic FEL pulses has opened up new horizons for the investigation of inner-shell electron dynamics in atomic and molecular systems [1]. So far, however, the limited temporal resolution (typically a few tens of femtoseconds) achievable with FELs has hampered the time resolution of these dynamics.
In this work we explored strong field-induced decay of doubly excited transient Coulomb complex Ar ∗∗ → Ar 2+ + 2e. We measured the correlated two-electron emission as a function of carrier envelop phase (CEP) of 6 fs pulses in the non-sequential double ionization (NSDI) of argon. Classical model calculations suggest that the intermediate doubly excited Coulomb complex loses memory of its formation...
Since its discovery in 1982 by L'Huillier and coworkers [1], non-sequential double ionization (NSDI) of atoms in strong laser fields has been the subject of numerous experimental and theoretical studies. Yet, the mechanisms that govern this process are not fully understood. Advances in ultra-fast laser technology have permitted the generation of light pulses with durations close to a single optical...
The transition from the multiphoton to the tunneling regime for ionization is characterized by the Keldysh parameter equation, where Up ∝ I × λ2. A value of γ smaller than 1 implies tunnel ionization. The scaling of the Keldysh parameter with the wavelength allows studying atomic and molecular systems deep in the tunneling regime, when mid-infrared wavelengths are applied. In the present study we...
Thin polymer films with lateral structures are expected to play an important role in future applications (e.g. plastic-based electronic devices). Such structures could be formed when blend films are spun-cast onto substrates patterned with self-assembled monolayers (SAM). The spin-coating process results in composition variations accompanied by surface undulations. We have studied both phenomena for...
Thin films, formed by polymer blends spun-cast from a blend/solvent solution onto a rigid substrate, are used in many practical applications (e.g. photoresist layers, dielectric coatings). Film preparation process is often accompanied by phase decomposition (PD) during the rapid evaporation of the solvent. PD is reflected in undulations formed on an air/film interface. We have studied the topography...
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