Ion imaging study of NO3 radical photodissociation dynamics: characterization of multiple reaction pathways.

Autor: Grubb MP; Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States., Warter ML, Johnson KM, North SW
Jazyk: angličtina
Zdroj: The journal of physical chemistry. A [J Phys Chem A] 2011 Apr 21; Vol. 115 (15), pp. 3218-26. Date of Electronic Publication: 2011 Mar 29.
DOI: 10.1021/jp200110e
Abstrakt: The photodissociation of NO(3) has been studied using velocity map ion imaging. Measurements of the NO(2) + O channel reveal statistical branching ratios of the O((3)P(J)) fine-structure states, isotropic angular distributions, and low product translational energy consistent with barrierless dissociation along the ground state potential surface. There is clear evidence for two distinct pathways to the formation of NO + O(2) products. The dominant pathway (>70% yield) is characterized by vibrationally excited O(2)((3)Σ(g)(-), v = 5-10) and rotationally cold NO((2)Π), while the second pathway is characterized by O(2)((3)Σ(g)(-), v = 0-4) and rotationally hotter NO((2)Π) fragments. We speculate the first pathway has many similarities to the "roaming" dynamics recently implicated in several systems. The rotational angular momentum of the molecular fragments is positively correlated for this channel, suggesting geometric constraints in the dissociation. The second pathway results in almost exclusive formation of NO((2)Π, v = 0). Although product state correlations support dissociation via an as yet unidentified three-center transition state, theoretical confirmation is needed.
Databáze: MEDLINE