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 ΔHf(NH)≲94±2 kcal mol−1. (c) The radiative lifetime of the (b 1Σt) state of NH has been redetermined and a value ≳2×10−3 s probably around 6×10−3 s has been obtained.