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[en] We present a new design of a time-preserving extreme-ultraviolet (XUV) monochromator using a semi-infinite gas cell as a source. The performance of this beamline in the photon-energy range of 20 eV–42 eV has been characterized. We have measured the order-dependent XUV pulse durations as well as the flux and the spectral contrast. XUV pulse durations of ≤40 fs using 32 fs, 800 nm driving pulses were measured on the target. The spectral contrast was better than 100 over the entire energy range. A simple model based on the strong-field approximation is presented to estimate different contributions to the measured XUV pulse duration. On-axis phase-matching calculations are used to rationalize the variation of the photon flux with pressure and intensity.
[en] Many labs try to boost existing data acquisition systems by inserting high performance intelligent devices in the important nodes of the system's structure. This strategy finds its limits in the system's architecture. The CHADAC project proposes a simple and efficient solution to this problem, using a multiprocessor modular architecture. CHADAC main features are: a) Parallel acquisition of data: CHADAC is fast; it dedicates one processor per branch; each processor can read and store one 16 bit word in 800 ns. b) Original structure: each processor can work in its own private memory, in its own shared memory (double access) and in the shared memory of any other processor (this feature being particulary useful to avoid wasteful data transfers). Simple and fast communications between processors are also provided by local DMA'S. c) Flexibility: each processor is autonomous and may be used as an independent acquisition system for a branch, by connecting local peripherals to it. Adjunction of fast trigger logic is possible. By its architecture and performances, CHADAC is designed to provide a good support for local intelligent devices and transfer operators developped elsewhere, providing a way to implement systems well fitted to various types of data acquisition. (orig.)
[en] We measured the relative ionization delays into the two spin-orbit components of the electronic ground states of Xe"+ and Kr"+ under the inuence of auto-ionizing intermediate and final states. The results are in good agreement with state-of-the-art calculations based on the time-dependent configuration-interaction singles (TDCIS) approach. (paper)
[en] A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup