The photodissociation of gaseous acetyl cyanide has been examined following excitation at 193 nm. CN X2Σ+ photofragments were probed via laser fluorescence excitation to determine their rotational, vibrational, and translational energy distributions. CN was produced in v‘‘ = 0 and 1 with mean rotational energy (13.5 ± 2) kJ mol-1, and v‘‘ = 2 with mean rotational energy (10 ± 4) kJ mol-1. Mean translational energies of the CN fragments were (32 ± 10) kJ mol-1. Ab initio electronic structure theory has been used to characterize the heat of formation for acetyl cyanide along with its geometries and vibrational frequencies. The acetyl cyanide heat of formation, ΔH 0 f,0, is predicted to be (−0.4 ± 8) kJ mol-1 using Gaussian-2 theory (G2). The theoretical results are used to compute bond dissociation energies of acetyl cyanide for further interpretation of the experimental photodissociation data. Evidence is presented that the majority of CN fragments are produced via dissociation of the parent acetyl cyanide to CH3CO + CN, with subsequent decomposition of the acetyl fragment. The alternate possible primary α-cleavage pathway to CH3 + OCCN is proposed as a possible source for the OCCN radical.

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Photofragmentations, state interactions, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization via E and V (B) states of HCl and HBr J. Chem. Phys. 138, 044308 (2013); 10.1063/1.4776260 Two-dimensional resonance enhanced multiphoton ionization of H i Cl; i = 35, 37: State interactions, photofragmentations and energetics of high energy Rydberg states J. Chem. Phys. 134, 164302 (2011); 10.1063/1.3580876 Polarizationresolved (2+1) resonanceenhanced multiphoton ionization spectroscopy of CF3I (6s) Rydberg states J. Chem. Phys. 98, 4355 (1993); 10.1063/1.464997[3+2] resonance enhanced multiphoton ionization of I and Br formed from the infrared multiphoton decomposition of CF3I and CF3BrTime-of-flight mass spectrometry has been used to examine the spatial aniso.tropy and. . translational energy of 1+ and CFt fragments resulting from resonant multtphoton excttatIon of CF 31 in the 300-306 nm range. These ion species are shown to be largely the photofragments from the single-photon direct dissociation of CF 3 1+ generated via a new resonant (2 + 1) multi photon ionization (MPI) transition. ghotoelectron spectroscopy shows that most of the parent CF 3 1+ is produced in its ground X 2E3/2 state by the resonant MPI process .. All the observed 1+ is formed via this parent ion photodissociation, while the observed CFt IS formed via statistical decomposition of the parent as well as parent ion photodissociation. The present results are discussed in the context of the current understanding of alkyl halide photodynamics.