The formation of excited state (2P) positronium
following the bombardment of untreated beryllium, copper
and gold surfaces by positrons in the energy range
10-500 eV is reported. This investigation finds
emission efficiencies in the low per cent region, in
accord with one other study of similar samples. Timing
spectra between the de-excitation Lyman-α
photons and annihilation gamma rays with a statistical
accuracy superior to that of other studies have been
generated. The interpretation of the data, including the
production mechanism of the excited atoms, is discussed.