A novel laser-based apparatus is presented utilizing high harmonic radiation for visible pump–EUV probe experiments on ultrafast processes. True femtosecond temporal resolution is achieved by a monochromator making use of dedicated narrowband multilayer mirrors rather than gratings for selection of single harmonic orders in the photon energy range between 66 and 73 eV. First applications of this new light source for electron spectroscopy on gas phase helium and xenon demonstrate the selection of a single high harmonic order with the intensity ratio between the selected and its adjacent harmonic not exceeding 10:1. A pump–probe study of hot electron production on a solid Pt(110) surface yields a cross-correlation corresponding to a temporal system resolution of 100 fs.

High energy high resolution monochromatic xray computed tomography using the Photon Factory vertical wiggler beamline Rev.

Measurements of the electron spin polarization parameter A have been performed for HBr in the energy region between the two ionization thresholds, Π3/22 and Π1/22. Using the multichannel quantum defect theory and formulas derived for the spin parameters in intermediate coupling between Hund’s cases (a) and (e), calculations for both the cross section and the A parameter have been performed. It is shown that the values of A for each Rydberg resonance change with n, following the change from Hund’s case (a) to case (e). In the approximations used in this paper, no simple relation between the sign of A and the value of J+, the rotational angular momentum of the ion core, was found. Values for the calculated angular asymmetry parameter β and the spin polarization parameter ξ are also presented. Since our calculations reproduced only part of the observed resonances, and since the measurements of the A parameter have been performed in relatively narrow energy regions, one could not perform an extensive comparison between theory and experiment. However, some of the peculiarities of the behavior of the A parameter observed experimentally have been qualitatively reproduced by our calculations.

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