AbstractMultilayer soap film structures, particularly the lead stearate variety have been used for several years as a dispersing element in soft X-ray spectrometers. These structures have a high scattering power, and if a high order of diffraction is used for the shorter wavelengths they provide good resolution throughout the 10-80 Å range. Structures having a 2d spacing smaller than that of lead stearate (100 Å) would provide greater dispersion and, hence, resolution in the first order for radiation in the 10-40 Å range. Details concerning the conditions required to build multilayer structures from the soaps of shorter fatty acids such as lead myristate, lead laurate, lead caprate, etc. are given. The various members of the soap film family are compared regarding their diffracting power both as a function of wavelength and the order of diffraction. Information is given regarding the dependence of the diffracting power, the width of the diffraction peak at half maximum and the peak to background ratio as a function of the number of double layers in a structure. The absorption occurring within a lead stearate and a lead laurate structure has been experimentally measured. Observed spectra can, thus, be corrected for the filtration caused by the soap film structure. The soap film family is evaluated as a dispersing element by comparing the various Structures with single crystals such as EDDT and KAP.
