Correlated Product Distributions in the Photodissociation of A ̃ State NO-CH 4 and NO-N 2 van der Waals Complexes.

This paper reports correlated product distributions for dissociation of the van der Waals complexes NO-CH 4 and NO-N 2 on their A ̃ state surfaces, providing detailed data sets against which calculations can be benchmarked. NO-CH 4 dissociation strongly favors small changes in the CH 4 angular momentum, with Δ J = 0 and 1 providing the bulk of the products. Conversely, the associated NO products show little constraint in terms of the rotational angular momentum transfer, with the full range of energetically accessible angular momentum states populated, although the distributions show minima. The lack of angular momentum transfer to methane accompanied by broad, structured, angular momentum transfer to NO gives the NO-CH 4 dissociation some qualitative similarities to NO-Rg complex dissociation. In contrast, for NO-N 2 , the cluster of highest probability products corresponds to high N 2 angular momentum and low NO angular momentum, with a sharp drop in the probability for populating the highest energetically accessible J states. For both the NO and N 2 products, there appears to be a constraint limiting angular momentum transfer at the highest energetically accessible rotational states. Both complexes show product distributions that include a component attributed to excitation from warm complexes, which provides insight into their internal energies. Interestingly, for NO-N 2 , the 44,475 cm -1 photolysis translational energy release distribution for N = 8 extends to energies beyond those accessible from the highest bound X ̃ states. This indicates either that there are long-lived (>100 μs) states above the X ̃ state binding energy or that there is another mechanism that also contributes to this distribution.