Specular properties of chemically etched polyethylene terephthalate foils in the soft X-ray region

Results from angular measurements of reflections of radiation at a wavelength of 13.5 nm of poly-ethyleneterephthalate (PETP) foils before and after chemical etching are described. The observed reduction in reflections at grazing incidence in contrast to reflections from ideal smooth sample is due to the characteristics of the surface microrelief of the foils and its changes due to etching. The results of this work can be used to study the spectral transmission of X-ray and UV diffractive filters made on the basis of track membranes.