Physics307L F09:People/Knockel/Lab6

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Electron Diffraction Summary

Electrons are waves that can diffract when going through crystals. Graphite is an allotrope of carbon where the carbon forms sheets of hexagonal patterns. The sheets of hexagonal carbon stack in a specific way that forms a crystal lattice that causes diffraction of electrons. I want to calculate certain dimensions of this lattice by measuring the diffraction of electrons through it when the electrons are aimed perpendicular to the sheets.

I have no clue what exactly I am measuring since 3D crystal latices form very complex diffraction patterns, but I know I am measuring some dimension of the crystal and calling it d. Maybe the physically significant measurement is 2*d or maybe 1/2*d, but this minor scaling can be done quickly (you won't have to redo the experiment and calculations...). SJK 21:09, 1 December 2007 (CST)
21:09, 1 December 2007 (CST)
21:09, 1 December 2007 (CST)

At the end of the day, the inner ring gave

d1=0.151(11)\, nm.

The outer ring gave

d2=0.088(6)\, nm.

The random error I have provided is due mainly to the fuzziness of the electron rings and Nik's imperfect (but still good) measuring abilities.

I am pretty sure there is a large source of systematic error, and that it is probably the equipment. Because 1) standard multimeters cannot measure very high voltages, 2) the circuits in this experiment were stupidly overcomplicated, and 3) the known dimensions of graphite are all much larger than I got, I am sure that the actual voltages that were accelerating the electrons were much less than those I used in my calculations, making the d values I have provided far too small.

link to my electron diffraction notebook

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