Two linear isomers, OPN and ONP, were formed in an Ar matrix at 16 K by ArF laser (lambda = 193 nm) photolysis of phosphoryl triazide, OP(N-3)(3), and comprehensively characterized by their mid- and far-IR spectra as well as N-14/15 isotopic data. Two intermediates, (N-3)(2)P(O)N and N3P(O)N-4, have been isolated in an Ar matrix and spectroscopically characterized. Photolysis of these intermediates using near-LTV/vis light (lambda > 320 rim) was shown to yield exclusively ONP, which under ArF laser irradiation selectively photo-isomerized to OPN. The photochemical and molecular properties of OPN and ONP are discussed on the basis of experimental and ab initio calculated results.