  The synthesis of platinum nitride by the laser ablation method is reported.
The spectroscopic results show that nitrogen is in interstitial sites of
platinum as N-units, contradicting the accepted configuration for PtN2 where it
is as N2-units. To elucidate this point we did density functional calculations
to correlate composition with nitrogen sites. For dilute nitrogen
concentrations, x < 0.2, nitrogen would be in six-fold coordinated sites
(octahedral interstices) as N-units. For 0.2 < x < 1.5, nitrogen would be in
tetrahedral interstices as N-units. Only for x > 1.5 the N2-configuration in
octahedral sites is attained.
