DESIGN AND PERFORMANCE OF A SOFT-X-RAY INTERFEROMETER FOR ULTRA-HIGH-RESOLUTION FOURIER-TRANSFORM SPECTROSCOPY

A Fourier Transform Soft X-ray spectrometer (FT-SX) has been designed and is under construction for the Advanced Light Source (ALS) at Lawre nce Berkeley National Laboratory as a branch of beamline 9.3.2. The sp ectrometer is a novel soft x-ray interferometer designed for ultra-hig h resolution (theoretical resolving power E/Delta E-10(6)) spectroscop y in the photon energy region of 60-120 eV. This instrument is expecte d to provide experimental results which sensitively test models of cor related electron processes in atomic and molecular physics. The design criteria and consequent technical challenges posed by the short wavel engths of x-rays and desired resolving power are discussed. The fundam ental and practical aspects of soft x-ray interferometry are also expl ored.