  We report on the creation and characterization of the luminescence properties
of high-purity diamond substrates upon F ion implantation and subsequent
thermal annealing. Their room-temperature photoluminescence emission consists
of a weak emission line at 558 nm and of intense bands in the 600 - 750 nm
spectral range. Characterization at liquid He temperature reveals the presence
of a structured set of lines in the 600 - 670 nm spectral range. We discuss the
dependence of the emission properties of F-related optical centers on different
experimental parameters such as the operating temperature and the excitation
wavelength. The correlation of the emission intensity with F implantation
fluence, and the exclusive observation of the afore-mentioned spectral features
in F-implanted and annealed samples provides a strong indication that the
observed emission features are related to a stable F-containing defective
complex in the diamond lattice.
