Braggs Law Exercise 3.4 X-ray powder defraction

[Sem]

In the lecture notes braggs law is stated as:

In exercise 3.4 the question is to find the first 5 peaks of the x-ray powder diffraction as a function os sin(2\theta). If I understand correctly the 2\theta comes from the fact that diffraction happens at 2 times the incident angle.

And in the answers of 3.4 braggs law is defined as:

But to me it seems that there is a factor 2 missing in the denominator. And that the answer should be: sin(2\theta) = \lambda / 2d

Or are we looking at a different diffraction order?

[anton-akhmerov]

You are right on both counts: the difference between \theta and 2\theta is due to the definition of the angle, but the factor of two is missing from the denominator. I’ve fixed the solutions now.