Intensity model and limitations
Both plots share a fixed source-based vertical scale. Intensity means spectral energy density
(arbitrary units per Å), not photon counts or integrated peak area.
The unfiltered Kramers continuum, Gaussian line widths, line strengths, rocking widths and
reflectivities are illustrative, not calibrated measurements. The original source coefficients
are retained; Kα₁:Kα₂ has area ratio 2:1. Kβ has its original broader width and empirical strength.
The editable bandwidth is an effective FWHM in θ (not 2θ). Gaussian reflection is evaluated in θ.
Narrow-band illustrative presets are 0.005° for Ge(111) and 0.003° for Si(111);
these are not universal material constants or measured Darwin widths. The previous flat-crystal
presets (Ge 0.15°, Si 0.1°) represented broad acceptance and passed both Cu Kα lines.
At Ge(111), the Cu doublet separation is about 0.035° in θ, so the narrow preset strongly
suppresses Kα₂ when tuned to Kα₁. Real rejection depends on divergence, strain, geometry,
number of reflections and non-Gaussian tails. Kα₁ isolation does not guarantee zero continuum
or harmonic contamination. Changing the crystal restores its bandwidth preset.
For Si/Ge(111), the nominally forbidden 222 order is omitted in this simplified model;
higher-order weights remain illustrative. Tube absorption, windows, polarization, divergence,
dynamical diffraction and detector response are not included. Curved/flat labels alone do not
establish real crystal performance. Quantitative comparison needs measured source spectra and
crystal rocking curves. Throughput below is energy integrated only over the displayed interval.