Diatomic line. Consider a line of atoms ABAB... AB, with an A-B bond lengtlh of sa. The form factors are fa» fp for atoms A, B, respectively. The incident beam of X-rays is perpendicular to the line of atoms. (a) Show that the interference condition is nd = a cos 0, where 0 is the angle between the diffracted beam and the line of atoms. (b) Show that the intensity of the diffracted beam is proportional to |f, - fB° for n odd, and to |f, + frl° for n even. (c) Explain what happens if fa = fB-

Diatomic line. Consider a line of atoms ABAB... AB, with an A-B bond lengtlh of sa. The form factors are fa» fp for atoms A, B, respectively. The incident beam of X-rays is perpendicular to the line of atoms. (a) Show that the interference condition is nd = a cos 0, where 0 is the angle between the diffracted beam and the line of atoms. (b) Show that the intensity of the diffracted beam is proportional to |f, - fB° for n odd, and to |f, + frl° for n even. (c) Explain what happens if fa = fB-