Angular-correlation distribution of positron-electron annihilation in GaAs

Angular correlation of positron annihilation radiations has been measured along the [100], [110], [111], [211], and [221] crystallographic axes in GaAs using the long-slit geometry. A pseudopotential calculation is carried out to understand the experimental data. There is good agreement between experimental and theoretical data. The structures seen in the low-momentum region of the data are interpreted in terms of the {σ} and {π} bonds of the sp³ hybridized bonding orbitals. The experimental data when compared with the calculated data reveal the presence of electron-positron many-body correlation effects.