Efficiency measurements of x-ray transmission gratings

Diffraction efficiencies of 44.8 A to 5.4 A X-rays by a freestanding gold transmission grating of 1.0 μm period have been measured, using characteristic-line radiation. Partial transparency of the grating affects the efficiency at the shorter wavelength and causes an increase in the efficiencies for orders m >= 1 over the long-wavelength values. Model calculations for a trapezoidal wire cross section are in good agreement with the measured efficiencies and allow the wire cross section to be determined. Gratings of this type have a high efficiency for wavelengths as short as 5 A and are, therefore, well suited for applications both in X-ray and XUV-astronomy. (author)