  The present study shows that the positrophilic electrons of a molecule dock
into the positron attractive potential region in the annihilation process under
the plane-wave approximation. The positron-electron annihilation processes of
both polar and non-polar fluorinated methanes (CH4-nFn, n=0, 1,..., 4) are
studied under this role. The predicted gamma-ray spectra of these fluorinated
methanes agree well with the experiments. It further indicates that the
positrophilic electrons of a molecule docking at the negative end of a bond
dipole are independent from the molecular dipole moment in the annihilation
process.
