Photodissociation of Jet-Cooled NO2 at 355 nm: Strong Alignment and Oscillations in the Rotational State Distributions of the NO(v =1) Fragment

Article abstract of DOI:10.1021/j100131a012

State-to state photodissociation of NO2 at 355 nm has been investigated by means of jet-cooling and one-photon laser-induced fluorescence probing techniques.The rotational distribution of nascent NO(v =1) from the fast predissociation of efficiently cooled NO2 shows pronounced oscillations of each spin-orbit and Λ-doublet component and bimodal distributions with preferred population at low and high J.Strong deviations from the statistical distributions of phase space theory are found.Alignment measurements for NO(v =1,J>5.5) from the dissociation of slowly rotating parent molecules are reported for the first time.The well-preserved rotational alignment with a fairly constant value of A⁽²⁾₀ = -(0.35 +/- 0.05) confirms that photodissociation at this wavelength is initiated by a ²A₁/²B₂ <- ²A₁ parallel electronic transition with less than 5percent contribution from another possible perpendicular transition ²B₁ <- ²A₁.The characteristic rotational distributions observed thus arise from this ²A₁/²B₁ transition.Our results clearly show that the energy flow among product rotational degrees of freedom is far from complete and that dynamical effects have to be considered important in the predissociation of NO2 via the ground-state surface.