Elastic Constants of Ice

Abstract

EXPERIMENTS on the thermal scattering of X-rays by ice crystals, made by Dr. K. Lonsdale, have revealed an interesting pattern consisting of strong diffuse bands which extend along the boundary of the second and third Brillouin zone, and to a lesser degree between the fourth and fifth zone. An explanation of this behaviour in terms of atomic vibrations seems scarcely possible. Another feature of ice difficult to explain with the help of vibrations is the Raman effect. A figure representing the Raman scattering of ice according to Cross, Burnham and Leighton¹ is reproduced herewith. Other experiments made by Hibben² agree with these in all essential features. One sees that there are two small peaks at about 200 and 600 cm.¹, and an enormous hump between 3,000 and 3,600 cm.¹. Cross, Burnham and Leighton try to explain this hump as a superposition of a great number of frequencies due to different ‘states of co-ordination’ of hydrogen bonds; but this assumption seems to be completely arbitrary, and I doubt whether even the order of magnitude of the range of frequencies can be explained in this way.