Estimate the wavelength of

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Crystal structure, bonding and diffraction · Crystal structure, bonding and diffraction

Condensed Matter Physics, Ch Diffraction: how a structure is actually measured

Problem

Estimate the wavelength of ((a)) an X-ray beam of energy

6.00\,\mathrm{keV}

, ((b)) a neutron beam of energy

2.00\,\mathrm{meV}

, and ((c)) an electron beam of energy

40.0\,\mathrm{eV}

, using the rules of Section 3.6. Copper's largest plane spacing is

d_{111}=2.087\,\mathrm{\mathring{A}}

, so no wavelength longer than

2d_{111}=4.174\,\mathrm{\mathring{A}}

can produce any reflection from copper at all (Section 3.3). Say which of the three beams could index a copper powder pattern and which could not.

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