TUNNELING MODES AND LOCAL STRUCTURAL ORDER IN AMORPHOUS ARSENIC

Pulsed nuclear-quadrupole-resonance (NQR) measurements have been performed in rhombohedral, orthorhombic, and amorphous (a-) arsenic. Measurements of T1 provide evidence of low-frequency disorder modes in a-As, while the NQR frequencies indicate that the bonding is predominately p-like in all three materials. The asymmetric NQR line shape of a-As indicates that bond-angle distributions inferred from x-ray scattering and continuous-random-network models do not result primarily from a distribution in bond hydridizations. © 1979 The American Physical Society.