A synchrotron radiation monochromator suppressing harmonics

The use of asymmetric Bragg reflection offers the possibility of separating wavelength bands belonging to a fundamental wavelength and its higher harmonics from each other. This is shown in an example calculated for X-rays. Especially for well collimated synchrotron radiation the subsequent use of symmetric and asymmetric reflections in a double-crystal arrangement results in different large shifts of the reflected peaks. This kind of synchrotron monochromator offers two important improvements with respect to other similar monochromator systems: (a) it is tunable to the harmonics of a fundamental wavelength in a large range, e.g. from 0.4 to 2.7 Å; and (b) it works harmonic free for each wavelength band on top of the Darwin curve.