Laser induced photodissociation of Hn3 at 266 nm. I. Primary products,photofragment energy distributions and reactions of intermediates

A detailed analysis of the primary photodissociation products resulting from the 266 nm laser photolysis of HN₃ is reported. The major primary fragments are N₂(¹Σ_g⁺) and NH(¹Δ). The NH(¹Δ) fragment is formed ? 99.8% in the ν = 0 level with ≈ 900 cm^?1 of rotational energy and ? 5000 cm^?1 of translational energy for the axially scattered fragments. A new chemiluminescent reaction is reported: NH(¹Δ) + HN₃ (¹A′) → NH ₂(²A₁) + N₃(²Π_g), which appears to be a major reaction channel of the primary NH(¹Δ) fragment. A kinetic analysis of this reaction and several other NH(¹Δ) reactions are the subject of the following associated paper. A correlation study of the NH(¹Δ) and N₂(¹Σ_g⁺) products with the dissociating states of HN₃ is made which requires a reassignment of the lower-lying HN₃ transitions.