Vacuum ultraviolet photodissociation of ammonia

Abstract

New measurements of the photofragment fluorescence excitation spectra of NH₂,ND₂(òA₁) and NH,ND(c¹Π) produced through the vacuum u.v. photodissociation of NH₃,ND₃ are reported. The spectra, which have been recorded at much higher resolution than previously, eliminate controversy concerning the predissociation of the B and C states and identify a contribution from the totally symmetric stretching mode in the vibronic structure. Measurements of rotational energy disposal in the NH(c¹Π) fragment are consistent with a photodissociation threshold at 136.5 ± 0.5 nm and a revised value for ΔH^⊖ _f0(NH)= 322.6 ± 7.1 kJ mol^–1.