Difference between revisions of "Bragg diffraction"
From Camilo's web
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The results of the measurement are shown in Figure 1 (below; note the error bars!). | The results of the measurement are shown in Figure 1 (below; note the error bars!). | ||
[[File:Bragg-measured.png|500px|frameless|center|Figure 1. Measurement of Bragg difraction]] | [[File:Bragg-measured.png|500px|frameless|center|Figure 1. Measurement of Bragg difraction]] | ||
We can identify clearly six peaks at $12^{\circ}$, $20^{\circ}$, $24^{\circ}$, $31^{\circ}$, $47^{\circ}$ and $59^{\circ}$. Considering that the wavelength of the source used to measure the diffraction is $\lambda=2.85\,\mathrm{cm}$, we obtain the following values for the interplane distance $d$: | We can identify clearly six peaks at $12^{\circ}$, $20^{\circ}$, $24^{\circ}$, $31^{\circ}$, $47^{\circ}$ and $59^{\circ}$. Considering that the wavelength of the source used to measure the diffraction is $\lambda=2.85\,\mathrm{cm}$, we use Bragg's law to obtain the following values for the interplane distance $d$: | ||
<center> | <center> | ||
Revision as of 18:45, 4 November 2020
Introduction
Procedure
Results & analysis
The results of the measurement are shown in Figure 1 (below; note the error bars!).
We can identify clearly six peaks at $12^{\circ}$, $20^{\circ}$, $24^{\circ}$, $31^{\circ}$, $47^{\circ}$ and $59^{\circ}$. Considering that the wavelength of the source used to measure the diffraction is $\lambda=2.85\,\mathrm{cm}$, we use Bragg's law to obtain the following values for the interplane distance $d$:
| Peak position ($^{\circ}$) | Diffraction order ($n$) | $d$ |
|---|---|---|
| 12 | 1 | (6.12 $\pm$ 0.25) |
| 20 | 1 | (3.77 $\pm$ 0.09) |
| 24 | 1 | (3.17 $\pm$ 0.06) |
| 31 | 1 | (2.50 $\pm$ 0.03) |
| 47 | 2 | (3.53 $\pm$ 0.03) |
| 59 | 2 | (3.01 $\pm$ 0.02) |
The actual separation between planes is $(3.80 \pm 0.05)\,\mathrm{cm}$, from which we can conclude that the peaks at 20$^{\circ}$ and at 47$^{\circ}$ correspond to the first and second diffraction orders of the planes. The other peaks, therefore, must be due to reflections with other planes of the crystal.