Novel X-ray optical systems for ultrafast spectroscopy and monochromators

The sensitivity of soft X-ray instrumentation for use in spectroscopy and monochromatization in the Hettrick-Underwood (HU) configuration can be significantly enhanced by replacing the common one-dimensional (1-D) variable line space grating by a two-dimensional (2-D), point-focusing reflection zone plate (RZP). To demonstrate the gain in the performance, we present examples of a flat-field spectrometer for the TiO2 fluorescence between about 390 eV and 530 eV and a femtosecond (fs) monochromator for an energy as low as 38.5 eV. In this context, the application to laser-based high harmonic generation (HHG) sources is discussed.