Photodissociation of N2O: J-dependent anisotropy revealed in N2 photofragment images

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Abstract
Photofragment imaging is used to measure the state-specific angular distributions of N 2 produced in the ultraviolet photodissociation of N 2 O . 2+1 REMPI (resonance enhanced multiphoton ionization) through the a ″ ( 1 Σ g + ) state is used to ionize individual rotational states of N 2 (ν=0) between J=40 and J=90 produced when N 2 O is dissociated by light of approximately 203 nm. The anisotropy parameter, β, used to characterize the angular distributions of the N 2 ion images, is greater than one for the lower rotational levels probed, and decreases to approximately zero for the highest rotational levels of N 2 . The positive beta parameter indicates that the products arise primarily from a parallel transition to the 2 1 A ′ ( 1 Δ) state in the parent molecule, and the decrease in β with increasing J of N 2 is due to increased bending in the parent N 2 O during dissociation. The ion images also allow us to assign transitions in a spectroscopically perturbed region of the N 2 photofragment REMPI spectrum and to reveal the production of N 2 products in the first vibrationally excited state.