X-Ray Diffraction: Solving for θ Using nλ=2dsinθ

[dawud]

Homework Statement

It's got a diagram in it so I have just attached a picture of it.

Homework Equations

nλ=2dsinθ

The Attempt at a Solution

I've really got no idea how to proceed with this one. I think you have to consider the effect of the thin film as well. Any ideas?

 

[haruspex]

From a quick reading up on the subject (of which previously I was blissfully ignorant), I would say that the incoming and outgoing beams must make the same angle to the planes in the crystal. Since it's powdered, the planes will be at every angle, but diffraction is only going to observed in those crystals with planes at the bisecting angle. So given the geometry of the source, sample and observed interference, you can deduce the angle of the crystal planes responsible.
Having done that, you can compute the plane spacing.

 

[BvU]

3. But you can make some assumptions. You have a $\lambda$, there are 2 $\theta$s. If n= 1, what is d for each of these ?

Once again, even quick replies cross. But there is a starting point.

 

[dawud]

Thanks a lot guys! I've got it now!