The differential anisotropy of the delayed angular distribution of the 198-keV gamma radiation following the inelastic scattering of protons by ${\mathrm{F}}^{19}$ has been investigated using various chemical forms of target materials. While in the case of a KF target, no appreciable time variation of anisotropy was observed within the time interval measured, in the cases of a CIF target and a ${\left({\mathrm{C}}_2{\mathrm{F}}_4\right)}_n$ target the characteristic patterns for the static quadrupole coupling of the polycrystalline state were observed. It was found to be necessary to interpret the patterns on the basis of a frequency distribution in the range of about ten percent. The mean values for the fundamental frequency of quadrupole coupling were found to be 12.4±0.6 Mc/sec for CIF and 9.0±0.4 Mc/sec for ${\left({\mathrm{C}}_2{\mathrm{F}}_4\right)}_n$. The strength of the electric field gradient $q$ of the nuclear environment in CIF was estimated as $q=1.07\mathrm{}\times {10}^{16}$ esu, following the empirical rule of Townes and Dailey. The nuclear quadrupole moment $Q$ was deduced to be $\left|Q\right({\mathrm{F}}^{19}, {\frac{5}{2}}^{+}\left)\right|=0.11\mathrm{}$ b. The uncertainty due to various causes of the moment $Q$ obtained was estimated to be about 20%.

• Received 23 December 1963

DOI:https://doi.org/10.1103/PhysRev.134.B539