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The photodissociation dynamics of the diazomethyl (HCNN) radical have been studied using fast radical beam photofragment translational spectroscopy. A photofragment yield spectrum was obtained for the range of 25 510–40 820 cm-1, and photodissociation was shown to occur for energies above 25 600 cm-1. The only product channel observed was the formation of CH and N2. Fragment translational energy and angular distributions were obtained at several energies in the range covered by the photofragment yield spectrum. The fragment translational energy distributions showed at least two distinct features at energies up to 4.59 eV, and were not well fit by phase space theory at any of the excitation energies studied. A revised C–N bond dissociation energy and heat of formation for HCNN, D0(HC–NN)=1.139±0.019 eV and ΔfH0(HCNN)=5.010±0.023 eV, were determined. [ABSTRACT FROM AUTHOR]

The photodissociation spectroscopy and dynamics resulting from excitation of the B 2A″←X 2A″ transition of CH2CFO have been examined using fast beam photofragment translational spectroscopy. The photofragment yield spectrum reveals vibrationally resolved structure between 29 870 and 38 800 cm-1, extending ∼6000 cm-1 higher in energy than previously reported in a laser-induced fluorescence excitation spectrum. At all photon energies investigated, only the CH2F+CO and HCCO+HF fragment channels are observed. Both product channels yield photofragment translational energy distributions that are characteristic of a decay mechanism with a barrier to dissociation. Using the barrier impulsive model, it is shown that fragmentation to CH2F+CO products occurs on the ground state potential energy surface with the isomerization barrier between CH2CFO and CH2FCO governing the observed translational energy distributions. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]