A variable-included-angle plane-grating-monochromator on an undulator for spectroscopy and microscopy at the Advanced Light Source

A new beam line (beam line 11.0) at the Advanced Light Source has been desi gned to employ an SX700 (Peterson, Opt. Commun. 40 (1982) 402) style variab le-included-angle plane-grating-monochromator. The extended range available from a specific grating is exploited to cover energies from the carbon 1 s absorption edge to the oxygen I s absorption edge with two different grati ngs (150 and 1200 lines/mm) with dispersion different by a factor of three. The phase space of a zone plate microscope can then be efficiently filled either at low or high resolution (R=2500 and 7500). At the same time the mo nochromator is designed to cover the energy range from 75 to 1500 eV using the same two gratings at high resolution for spectroscopy, A deformable mir ror pair will re-focus to a monochromatic spot 5x10 mum, matched into the a cceptance of a fluorescence spectrometer. The monochromator will operate in vertically collimated light and the free choice of focusing parameter prov ides a guarantee of high resolution even when the power loading is high. Ho wever, we will provide a thermally engineered pre-mirror so that the high r esolution requirement at low photon energy can be met without loss of effic iency. (C) 2001 Published by Elsevier Science B.V.