Optical absorption measurements in the soft-x-ray range

We report measurements of optical-absorption coefficients obtained by techniques not requiring free-standing films. The results of these methods are compared with data obtained by inelastic electron scattering. We find that, as expected, absorption data obtained with smoother substrates yield results with more detail in the regions with rich structure. The spectra resulting from samples evaporated onto a Si diode vacuum-UV detector with a KCI buffer layer yield results that are quite similar to the results for inelastic electron scattering.