A beam of electrons is incident on a crystal with in-plane atomic spacing D = 2.2 Å and out-of-plane spacing C = 1.55 Å, where C and D have the same meaning as on the handouts and class notes.
(a) If the energy of the beam is 50 eV, at what angle ? will the diffracted beam emerge? Will the diffracted beam be strong or weak?
(b) At what angle(s) could a strong beam emerge (if the energy had the appropriate value)? (You may use any value of m and n that you prefer, but m=n=1 is probably simplest.) What would the beam energy have to be in order to create a strong diffracted beam at this angle?