The interatomic spacing in a crystal of table salt is 0.281 nm. This crystal is being studied in a neutron diffraction experiment, similar to the one that produced the photograph in the figure. How fast must a neutron (mass = 1.67 x 10^-27 kg) be moving to have a de Broglie wavelength of 0.281 nm?

Answer 1

λ = h/p = h/m•v,
v = h/m•λ =
=6.63•10^-34/1.67•10-27•0.281•10^-9 =
= 1420 m/s