Icosahedral quasicrystals applied as a harmonic-free crystal analyser

The use of quasicrystals as crystal analysers has been studied in monochromatic X-ray synchrotron radiation applications. The quasiperiodicity of their structures gives a theoretical third-harmonic rejection factor of up to 5 × 10^-4 when the icosahedral (20,32) Bragg peak is used. This ratio is compared with the intrinsic value for silicon perfect crystals in Bragg configuration, namely 2 × 10^-2. This rejection factor may be increased for some well defined configurations, as reported elsewhere for the case of periodic crystals.