Abstract
Pulsed nuclear quadrupole resonance (NQR) experiments have been performed on three forms of elemental arsenic: amorphous (), rhombohedral (), and orthorhombic (). The temperature dependence of the spin-lattice relaxation time () provides evidence for the existence of disorder (tunneling) modes in -As. It is found that the NQR line shape of -As is highly asymmetric, and this asymmetry is attributed to a distribution of dihedral angles in -As. The observed NQR frequencies indicate that the amount of bonding admixture is different in each material (-As: 3%, -As: 7%, -As: 10%). Simple calculations in comparison with x-ray results indicate that the bonding configurations in these three forms of arsenic do not necessarily correspond to maximum overlap of bonding orbitals on adjacent atoms.
- Received 14 April 1980
DOI:https://doi.org/10.1103/PhysRevB.22.3903
©1980 American Physical Society