Crystal diffraction using Bragg's Law

[frederer]

Homework Statement

You wish to study a material with a cubic crystal structure with
three orthogonal sides of length a = 0.3nm. What is the
longest possible wavelength of the X-ray source you could use
to reveal the (211) Bragg peak of the crystal?

Homework Equations

nλ = 2dSinθ (Bragg's Law)

d = a/sqrt(h^2 + k^2 + l^2)

The Attempt at a Solution

Hi. Ok so i think i need the two formulae above to solve this question.

You can figure out d simply enough by slotting in the numbers,
giving λ = 2.44Asinθ
but the trouble I am having is how to calculate the angle θ. If you draw out the
cube in question you can see the angles formed between in the plane but
I am not sure which angle, if one of these angles at all is required to solve
the question. Any help would be much appreciated.

 

[phanivaka]

Dear all
i am struggling on a question regarding powder XRD. Can anybody please help me on this.

Question: I have lambda(X-ray wavelength used) and 2theta(100% intense peak) value of a crystal compound; with that data can anyone calculate the "d(distance between two planes)" value of that crystal using braggs law(i.e. nλ = 2 d sinΘ) theoritically. If so please explain me with an example.
Note: What is the n value we need to apply in that formula.