The electric field gradient at ¹⁹F in diamond

Time Differential Perturbed Angular Distribution (TDPAD) studies of fluorine isotopes implanted into diamond have revealed two distinct quadrupole interaction frequencies, 59 MHz and 23 MHz. These signals are consistent with cluster model molecular orbital calculations representing fluorine on substitutional and interstitial sites. At the substitutional site the electric field gradient is large but the fluorine ion experiences only a small deviation from tetrahedral symmetry resulting in the small TDPAD resonance. Conversely, at the interstitial site, where the electric field gradient is smaller, the distortion from tetrahedral symmetry is large and this gives the higher TDPAD frequency.