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Homework Statement
If [tex] a_1 a_2 a_3[/tex] are the unit vectors of a real space lattice, then the so-called “reciprocal lattice” is defined by the unit vectors [tex]b_1 b_2 b_3[/tex] where:
[tex] b_1 = \frac{2\pi a_2 \times a_3}{a_1 \cdot a_2 \times a_3} [/tex]
[tex] b_2 = \frac{2\pi a_3 \times a_1}{a_1 \cdot a_2 \times a_3} [/tex]
[tex] b_3 = \frac{2\pi a_1 \times a_2}{a_1 \cdot a_2 \times a_3} [/tex]
Consider a plane hkl in a crystal lattice.
(a) Prove that the reciprocal lattice vector [tex]G = hb_1 + kb_2 + lb_3[/tex] is perpendicular to this plane.
(b) Prove that the distance between two adjacent parallel planes of the lattice is
[tex] d(hkl) = \frac{2\pi}{|G|} [/tex]
Homework Equations
[tex] a \cdot b = |A||B| cos \theta [/tex]
[tex] a \times b = |A||B| sin \theta [/tex]
The Attempt at a Solution
So far I have subsituted in the values of a1/2/3 into the given equation to give:
[tex]G = h\frac{2\pi a_2 \times a_3}{a_1 \cdot a_2 \times a_3} + k\frac{2\pi a_3 \times a_1}{a_1 \cdot a_2 \times a_3} + l\frac{2\pi a_1 \times a_2}{a_1 \cdot a_2 \times a_3}[/tex]
but I am not quite sure how to show that this is perpendicular.
I have added the dot and cross product as I feel these may be useful?