The spectral distribution of absorption in the ultra soft x-ray region (25-85 angstroems) for gases and plastic foils.

New and improved measurements have been made of the absorption of ultra soft x-radiation by light gases and plastic foils. A short introduction to the place of x-ray absorption in the historical development of x-ray research is followed by a discussion of the reasons for interest in absorption in the ultra soft x-ray region A review of the few x-ray absorption measurements that have been made in this region by other workers together with an outline of the present investigation complete the first chapter. Two different absorption spectrometers were designed and are described in Chapter 3. The gas absorption measurements were confined to a grazing incidence concave diffraction grating instrument, while a small radius curved crystal spectrometer was employed for the plastic investigation. No natural crystals occur possessing lattice spacings sufficiently large to permit Bragg reflection of the wavelengths of interest (up to 85 A). Artificial fatty acid crystals constructed by a method introduced in the thirties by Langmuir and Blodgett, were developed to fill this gap. The examination and development of these crystals is described in the fourth chapter. The experimental techniques used, involved the production of characteristic emission line radiation and the use of non integrating x-ray detection methods and are detailed in Chapter 5. In the concluding chapter the results of the investigation are compared with other published absorption data and the theoretical treatments of Hall and Bearden. These wave mechanical treatments are shown to be inadequate for the L shell, however, better agreement is obtained between the Bearden K-shell theory and experiment.