ELECTRON-PHONON INTERACTION IN B-12 ICOSAHEDRA

By the interaction between electrons and pairs of phonons, which are t he slightly modified breathing modes F-1u and F-2u of the free icosahe dron, the electron trapping levels are generated, which are known to i nfluence the properties of the boron-rich solids essentially. Dependin g on the number of phonon pairs involved up to six levels below the co nduction band of beta-rhombohedral boron occur, whose ionisation energ ies are multiples of 0.188(2) eV equal to the sum of the energies of t he phonons involved. On beta-rhombohedral boron and boron carbide is s hown that in consequence of the formation of such levels the correspon ding phonons in the lattice vibration spectrum are quenched.