On a few points concerning the vacuum-ultraviolet photolysis of NH3

Some aspects of the vacuum‐ultraviolet photolysis of NH₃ have been revised on the basis of new experimental results: (a) A normalized fluorescence excitation spectrum of the NH₂($Ã$ ²A₁) has an apparent energy threshold at 193±1 nm corresponding to the excitation of the 6–7th levels of the ν₂^′ mode of NH₃ ($Ã$ ¹A₂^″). (b) A new value for the energy threshold of the formation of NH(c ¹π) is 126±1 nm, corresponding to a ΔH_f(NH)≲94±2 kcal mol⁻¹. (c) The radiative lifetime of the (b ¹Σ^t) state of NH has been redetermined and a value ≳2×10⁻³ s probably around 6×10⁻³ s has been obtained.