plane around [111] and in out-of-plane sections through the lobe. A comparison
is made with results measured over the same sector of the
plane at an indicated temperature of 201 K.
ENERGY DISPERSIVE DIFFUSE SCATTERING STUDIES OF ADAMANTANE (C10H16) AND DIAMOND. John S. Reid, School of Physics, The University, Aberdeen, Scotland. Moreton Moore & Grzegorz Kowalski, Department of Physics, Royal Holloway, University of London, Egham, Surrey UK. on leave from the Institute of Experimental Physics, University of Warsaw, Poland
We have used the technique of energy dispersive diffuse scattering (Reid, 1993) to explore rotational disorder scattering in adamantane and structural disorder scattering from platelets in natural diamond.
Adamantane is a plastic molecular crystal which shows lobes of diffuse
scattering along (111( directions at room temperature, due to constrained
rotational motion of the highly symmetric C10H16
molecules. We set out to measure the absolute diffuse scattering in the lobes
and the structure of that scattering, in order to provide a much needed
comparison with the rotational predictions of molecular dynamics models.
Single crystals of adamantane were grown by sublimation. They were left to
anneal for over 25 years. Results of diffuse scattering measurements are
presented over a sector of the
plane around [111] and in out-of-plane sections through the lobe. A comparison
is made with results measured over the same sector of the
plane at an indicated temperature of 201 K.
The energy dispersive technique has also been applied to measuring the diffuse scattering seen as short spikes extending out in [100] directions from certain reflections in type Ia natural diamonds (Moore et al 1993). The sensitivity of the energy dispersive technique is such that these diffuse spikes can be traced out to the zone boundary.
Moore, Moreton et al. (1993), Diamond Rel. Mat., 2, 115 - 120
Reid, John S. (1993), Acta Cryst. A49, 190 - 198