VUV HIGH-RESOLUTION AND HIGH-FLUX BEAMLINE FOR CHEMICAL-DYNAMICS STUDIES AT THE ADVANCED LIGHT-SOURCE

An undulator beamline, consisting of VUV high resolution and high flux branch lines, devoted to chemical dynamics experiments has been designed at the Advanced Light Source. The radiation source is an undulator having a 10-cm period, and the fundamental in the energy range from 6 to 30 eV is utilized by the experiments. The higher harmonics of the undulator due to the operation at high K values is suppressed by a novel gas filter. In the first branch, high-flux 2% bandwidth radiation is directed toward an end station for photodissociation. A photon flux calculation predicts 1016 photon/s at this end station. In the second branch, highly monochromatized radiation is sent to an end station for photoelectron spectroscopy and photoionization studies. For this purpose a vertical dispersion 6.65-m off-plane Eagle mounting was chosen for the monochromator in anticipation of achieving a resolving power of approximately 5 X 10(4) with a 1200 grooves/mm grating and 1 X 10(5) to 2 x 10(5) with a 4800 grooves/mm grating.