Beam assisted molecular rearrangement observed by TDPAD for fluorine complexes in diamond

Time dependent perturbed angular distribution (TDPAD) measurements have consistently revealed two unique sites for recoil implanted ¹⁹F in different types of natural diamonds. These correspond to quadrupole coupling constants of 63(2) and 56(2) MHz. The first corresponds to the formation of a C-F bond at an intrabond site and the second is interpreted as a distorted substitutional site. A third resolved coupling constant of 33(3) MHz is associated with a broadly distributed site with random electric field gradient orientation which might be indicative of local amorphous conditions and is interpreted as arising from the formation of H-F molecular complexes. A strong dependence on the incident proton dose of this fraction has been observed for all types of natural diamonds. A model proposed for such an effect involves a beam-assisted mechanism which accounts for disruption of existing hydrogenic molecular complexes and rearrangement of ions under the influence of intense electronic excitation caused by the incident proton beam. Such results give new insights on ¹⁹F as a TDPAD probe. Its small size and chemical affinity render it particularly appropriate for studies of molecular complexes with TDPAD.