Andy Buffler, UCT Physics: Slides from colloquium given on 25 ...

The effects of temperature on the intensities of X-rays scattered
<strong>from</strong> crystals ... research programme covered temperature range
<strong>from</strong> liquid air to about 700 °C ...
... found that Debye’s formula was valid at low temperatures, but
not high ones.
Two very important papers ...
RW James, I Waller and DR Hartree, “An investigation into the existence of
zero­point energy in the rock-salt lattice by an X-ray diffraction method.”
Proc. Roy. Soc. A, 118 (1928) 334.
... first direct quantitative check on the existence (and amount)
of “zero point energy” in the crystal lattice of NaCl ...
... confirmed in a later paper dealing with aluminium ...
RW James and GW Brindley, “A quantitative study of the reflection of X-rays <strong>from</strong>
crystals of aluminium.” Proc. Roy. Soc. A, 125 (1929) 401.