Table 2. Upper boundary for the energy resolution calculated from the FWHM of Si(111) and the Si(311) crystal rocking curves of the second crystal of the DCM at 42.40 and 59.82, 76.95keV, respectively.

Rocking curves were determined by scanning the second monochromator crystal against the first crystal and thus giving an upper bound of the energy resolution.

Crystal	Energy (keV)	Theoretical rocking curve (FWHM rad1)	Measured rocking curve (FWHM rad1)	E/E (meas) (FWHM)
Si(111)	42.40	8.38	9.79 (9)	2.1 104
Si(311)	59.82	2.38	3.99 (7)	6.3 105
Si(311)	76.95	1.57	5.3 (1)	1.07 104