Question

A beam of X-rays with a wavelength Ć of 0.179nm is directed at an iron crystal whose planes have a spacing of 0.1013nm. How many diffraction peaks (each arising from a different order n) are possible?

I'm really not sure how to go about solving this. Any help is appreciated. Thank you!

Answer 1

Bragg’s Law
nλ =2dsinθ,
n=2dsinθ/λ.
Max n when sinθ=1 =>
n=2d/λ=2•0.1013/0.179 = 1.13.
Since n has to be integer,
n=1 =>
the maxima of the 1st order on the both sides of the central max

Answer 2

Thamk you for your help.