Diffraction orders of grazing incidence

[Hamedo]

Homework Statement

We have a honeycomb lattice. There is an incident wave of 400 nm, whose wavevector has an angle of 75 degree with the surface's normal. This problem is similar to LEEDS ( low energy electron diffraction).

Homework Equations

What is the condition of diffraction i.e. which orders achieve Von-Laue conditions ?

The Attempt at a Solution

I tried to put that |G_2d|<=2*|k_s|, where G is the 2-dimension reciprocal lattice vector, and k is the length of the scattering wavevector ( |K_incidence|=|K_scattering|).

 

[Rohan1997]

hmm that's interesting, did you take into account the lattice surface structural constant into account?