Transmission grating efficiencies for wavelengths between 5.4 Å and 44.8 &Aring

Diffraction efficiencies of 44.8-5.4-A X rays by a free-standing gold transmission grating of 1.0-micron period have been measured, using characteristic line radiation. Partial transparency of the grating affects the efficiency at the shorter wavelengths and causes an increase in the efficiencies for orders m not less than 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 extreme UV astronomy