Ethyl radicals were produced by flash pyrolysis of n-propyl nitrite. Formaldehyde and nitric oxide are formed as side products in the pyrolysis. In addition, experiments using partially deuterated propyl nitrite were carried out.
(a) Symmetrized image of the H-atoms detected upon photodissociation of ethyl at 250 nm and (b) the same image but reconstructed with pBASEX.
Angular distribution of the hydrogen atoms: While the slow H-atoms (lower trace) show an isotropic angular distribution, a significant anisotropy is found for the fast atoms (upper trace).
The translational energy distribution derived from the image (perpendicular polarization). The fast H-atoms are fitted with a Gaussian function while the slow ones are fitted with a one-parameter distribution function (see text for details).
Doppler scan of the H-and D-atoms obtained from the pyrolysis of partially deuterated n-propyl nitrite. From the small amount of deuterium observed, significant contributions of formaldehyde to the H-atom signal are ruled out.
The Doppler-profile of CD3CH2 photofragments shows a preference of D-loss and thus a high degree of regioselectivity.
Time-delay scans of the D-atom signal from CD3CH2. The dotted line corresponds to high extraction voltages that permit to map all D-atoms onto the detector. To record the delay trace represented by the full line, the fields in the ion optics were set in a way to discriminate against D-atoms with large translational energy. The presence of a dissociation channel with a slow rate of D-atom formation is evident.
Structures and energy levels possibly involved in the photodissociation of ethyl. The graph follows a similar figure given by Amaral et al. 9 See text for details of the energetics.
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