A. Coker

Influence of intermolecular bonding on nuclear quadrupole interaction tensors in solid halogens

The role of intermolecular bonding in solid halogens is studied using the self‐consistent charge extended Huckel procedure. It was found that the hybridization of s and d orbitals to p orbitals of the halogen plays a very important role in the intermolecular bonding. In particular it was found that the hybridization is stronger with (n+1) s and nd orbitals where n=3,4,5 for chlorine, bromine, and iodine than for ns orbitals. Using the ns, (n+1) s, np, and nd orbitals for the halogen atom and a number of its nearest neighbors, the wavefunctions of the interacting molecules have been calculated, and using these calculated wavefunctions, the field‐gradient tensors have been evaluated for all three systems. The asymmetry parameters are found to be 0.06, 0.18, 0.23 for chlorine, bromine, and iodine, respectively. The quadrupole coupling constants were found to be −109.10, −779.31, and −1923.97 MHz for chlorine, bromine, and iodine. Relativistic corrections have been incorporated in the evaluation of the field ...

Explanation of irregular trend in19F* (I=5/2) nuclear quadrupole interaction in CF4, SiF4, and GeF4

A theoretical investigation of the electric field gradient at excited nuclei19F*(I=5/2) of the tetrafluorides CF4, SiF4, and GeF4, has been carried out using the Self-Consistent Charge Extended Hückel procedure to obtain the electronic wave functions. The values of ¦e2qQ¦ that have been obtained are 50.3, 30.4, and 36.3 MHz for CF4, SiF4, and GeF4, respectively, agreeing with the trend in recent experimental data. Physical reasons are presented for the trend, which is irregular as compared to expectations from Townes-Dailey Theory which would have predicted a continuus decrease in going from CF4 to GeF4.

Structural information about tellurium and iodine implanted in semiconductors from analysis of Mössbauer nuclear quadrupole interaction data

We have analyzed through electronic structure investigations, based on a model of an impurity atom trapped close to a substitutional site adjacent to a vacancy, the nuclear quadrupole interactions of125Te and129I implanted in a number of group IV and III–V semiconductors. Our analysis supports the proposed model for these impurity systems and leads to distances between the impurity and nearest neighbour host atoms close to the normal covalent bond distance, with one exception,129I in GaSb, a possible physical reason for which is pointed out. The general nature of our conclusion for the impurity-host bond distances, in particular, its relationship to bond lengths associated with adsorbed halogen atoms at surfaces of semiconductors is discussed.