Spin resolved electron scattering and photoionization with xenon adsorbates in direct comparison with the corresponding gas phase data

Heinzmann U. Spin resolved electron scattering and photoionization with xenon adsorbates in direct comparison with the corresponding gas phase data. In: Teubner PJO, Weigold E, eds. Inst. Phys. Conf. Ser. No. 122, Correlation and Polarization in Electronic and Atomic Collisions and e-2e Reactions. Australia: Flinders University; 1992: 237

Quasi-real-time photon pulse duration measurement by analysis of FEL radiation spectra

For photon diagnostics at free-electron lasers (FELs), the determination of the photon pulse duration is an important challenge and a complex task. This is especially true for SASE FELs with strongly fluctuating pulse parameters. However, most techniques require an extensive experimental setup, data acquisition and evaluation time, limiting the usability in all-day operation. In contrast, the presented work uses an existing approach based on the analysis of statistical properties of measured SASE FEL spectra and implements it as a software tool, integrated in FLASH's data acquisition system. This allows the calculation of the average pulse durations from a set of measured spectral distributions with only seconds of delay, whenever high-resolution spectra are recorded

Time-resolved investigation of the optical phase change as a potential diagnostics tool for extreme-ultraviolet free-electron-laser pump and optical probe experiments

Measurement of transient optical properties (reflectivity and transmissivity) is performed widely in extreme-ultraviolet (XUV) pump–optical probe experiments to study the transient state of irradiated materials. In order to extend the material diagnostics, here we propose an additional measurement of the transient phase change of the optical probe pulse. It can be recorded in parallel to other transient optical properties, enabling access to full information on the complex refractive index and thickness of the radiation-modified material layer. The latter is essential for investigations of phase transitions progressing in XUV (and x-ray) irradiated materials. We perform a computational study that clearly shows that the measurement of the optical phase from a probe pulse at correctly tuned pulse parameters can provide a signal strong enough to extract information on transient material properties. The calculations suggest that in some cases, it is even more preferable to measure the transient phase change than other optical parameters. Such phase measurement, feasible with modern experimental setups, can then be a basis for an improved diagnostics tool for the temporal characteristics of an ultrashort XUV pulse