New transmission-type X-ray filters consisting of amorphous multilayer films

New transmission-type X-ray filters have been developed. The filters consist of X-ray-amorphous metal (less than 30 Å)/metalloid (∼10 Å) multilayer films sputter-deposited on X-ray-transparent polymer substrates. Such metal/metalloid multilayer films show only very broad diffraction peaks, since the metal and metalloid layers forming the multilayer films are usually X-ray amorphous if the layers are sufficiently thin. The filters use the wavelength-dependent absorption phenomena near absorption edges of elements to reduce the intensity of transmitted X-rays, without generating any crystalline sharp peaks which cause serious problems in experiments such as fluorescence XAFS measurements. The multilayer-film filters were prepared by a multi-target magnetron sputtering deposition technique, paying special attention to the homogeneity of the layer thickness by spinning substrates of the films. The filters are useful in reducing the intensity of undesirable fluorescence emissions and improving the signal-to-background ratios of data acquired in various measurements using a solid-state detector.