Dynamics of the O(1D)+CH4 reaction: Atomic hydrogen channel vs molecular hydrogen channel

Abstract

The O(1D)+CH4 reaction has been investigated using a new universal crossed molecular beam apparatus. Both the atomic hydrogen channel (CH3O/CH2OH+H) and the molecular hydrogen channel (H2CO/HCOH+H2) have been experimentally observed in this reaction. The experimental results suggest that the main atomic hydrogen channel in the O(1D)+CH4 reaction should be CH2OH (hydroxymethyl)+H, while the CH3O (methoxy)+H channel is at most a minor process. From the product angular distribution measurements, it is clear that the radical products (CH2OH and/or CH3O) in the hydrogen atom channel are only slightly backward scattered relative to the O(1D) beam direction, indicating that this product channel mainly goes through a long-lived intermediate pathway. The slightly backward scattered products are possibly due to other reaction mechanisms. For the molecular hydrogen channel, the product angular distribution obtained from simulation also seems isotropic, implying that this channel also likely goes through a long-lived intermediate pathway.