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

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Homework Help Overview

The discussion revolves around solving for the angle θ in the context of X-ray diffraction using the equation nλ=2dsinθ. The original poster mentions a diagram related to the problem but expresses uncertainty about how to proceed, particularly regarding the influence of a thin film.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the geometry of the incoming and outgoing beams in relation to the crystal planes, noting that diffraction is observed only at specific angles. There is a suggestion to consider the implications of having multiple angles and the relationship between wavelength and plane spacing.

Discussion Status

The conversation has progressed with participants offering insights into the geometric considerations of the problem and the assumptions that can be made. The original poster indicates a shift in understanding, suggesting that some guidance has been effective.

Contextual Notes

There is mention of a diagram that is crucial for understanding the problem, but the original poster's uncertainty about the thin film effect remains a point of discussion.

dawud
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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?
 

Attachments

  • 20140211_183605.jpg
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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.
 
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.
 
Thanks a lot guys! I've got it now!
 

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