Study of a rhombohedral graphite X-ray filter using the sphere-in-contact model

[Display omitted] •Sphere-in-contact model of rhombohedral graphite.•Molecular channels along 22.7° from surface normal.•X-ray Cu Kα and Cu Kβ are filtered by rhombohedral graphite filter. We have studied with the sphere-in-contact model the structure of rhombohedral graphite and found that there are molecular channels 22.7° with respect to the material symmetry axis. We show via theoretical simulations with the Laue equation, Kramers equation and Duane-Hunt law that X-ray radiation (λ