Figure 1
The two-dimensional neutron scattering pattern from opal taken at a wavelength of 10 Å, showing the variation in the resolution of the 111 peak. The weak second diffraction peak at a scattering vector that is (8/3)1/2 ≃ 1.61 times that of the first-order peak is consistent with a system of close-packed lattice of noncrystalline silica spheres (Sosnowska & Shiojiri, 1999). (The incident beam without the sample is superimposed on the beam stop.) |