Photodissociation of O2 in the Herzberg continuum. II. Calculation of fragment polarization and angular distribution

Abstract

Articles you may be interested inIon-pair dissociation dynamics of O2 in the range 17.2-17.5 eV studied by XUV laser and velocity map imaging method State-to-state photodissociation dynamics of OH radical via the A 2 Σ + state: Fine-structure distributions of the O ( 3 P J ) product Parallel and perpendicular components of the Herzberg I, II, and III transitions contribute to the photodissociation of O 2 in the Herzberg continuum. The photodissociation dynamics determines the O( 3 P j ), jϭ0,1, and 2 atomic fine-structure branching ratios and angular distributions, which were determined in ion imaging experiments at ϭ236, 226, and 204 nm by Buijsse et al. ͓J. Chem. Phys. 108, 7229 ͑1998͔͒. In the preceding paper we presented potential energy curves for all eight ungerade O 2 states that correlate with the O( 3 P)ϩO( 3 P) dissociation limit, and the R-dependent spin-orbit and the nonadiabatic radial derivative couplings between these states. Here, we employ these potentials and couplings in a semiclassical calculation of the fine-structure branching ratios, atomic polarizations, and fine-structure resolved anisotropy parameters. We discuss the adiabaticity of the dissociation by comparing the results with adiabatic and diabatic models. The O( 3 P j ) 2ϩ1 REMPI detection scheme used in the experiment is sensitive to the polarization of the atomic fragments. We predict an important effect of the polarization on the anisotropy of the jϭ1 and jϭ2 ion images at low energies ͑Ͼ236 nm͒. The agreement between the semiclassical calculations and experiment is reasonable, possible explanations for the remaining differences are discussed.

The photodissociation dynamics of ozone at 193nm: An O(D21) angular momentum polarization study

“…Simpler models that allow interpretation of electronic polarization information in more complex systems are also available. 8,[11][12][13][14] In the present work, the technique of velocity-map ion imaging is applied to a study of the molecular photodissocia tion of ozone at 193 and 205 nm, which has allowed deter mination of O (1D 2) electronic orbital angular momentum po larization moments up to and including those of rank K =4. Together with information about the velocity distribution of the O (1D 2) photofragments, we illustrate how the polariza tion data can be used to unravel the dissociation mechanism(s) operating in this important atmospheric molecule.…”

Theoretical study on the photoabsorption in the Herzberg I band system of the O2 molecule

“…Using these initial and final state wavefunctions, we obtained the Z, X, and M electronic transition moment parameters in Eqs. (19)- (21). In the calculation of the M parameter, we used the CSF representation instead of the sumover-states representation, and evaluated the parameter by solving linear equations employing the iterative algorithm by Pople et al [29] Because these two representations are related by the unitary transformation, we should obtain the equivalent value by the two representations.…”

“…For example, they calculated the anisotropy parameters by using their theoretical potential curves and the experimental values [6] for the parallel and perpendicular branching ratios of the Herzberg transitions. If we have accurate transition moments for the initial excited state populations, we can obtain genuine theoretical anisotropy parameters and remove the ambiguity discussed in [21]. Another interest to study the anisotropy parameter is the relatively large difference in the existing experimental values.…”

“…Vroonhoven et al [20,21] performed theoretical studies on the photodissociation process from the Herzberg band excitations, and obtained the physical insight for the potential energy curves in the dissociation region. For example, they calculated the anisotropy parameters by using their theoretical potential curves and the experimental values [6] for the parallel and perpendicular branching ratios of the Herzberg transitions.…”

Raman association of H2 in the early universe

“…We use the parity convention defined by van Vroonhoven and Groenenboom. 16 We denote 2J þ 1 by [J] throughout.…”