DYNAMICAL STUDIES OF THE OZONE ISOTOPE EFFECT: A Status Report

Abstract

Dynamical studies of the recombination of O and O2 to form ozone are reviewed. The focus is the intriguing isotope dependence of the recombination rate coefficient as observed by Mauersberger and coworkers in the last decade. The key quantity for understanding of this dependence appears to be the difference of zero-point energies of the two fragmentation channels to which excited ozone can dissociate, i.e., X + YZ <-- XYZ* --> XY + Z, where X, Y, and Z stand for the three isotopes of oxygen. Besides the isotope dependence, the variation of the recombination rate coefficient with pressure and temperature is also addressed. Despite the numerous approaches of recent years, the recombination of ozone is far from being satisfactorily explained; there are still several essential questions to be solved by detailed theoretical analysis. We mainly discuss--and critically assess--the results of our own investigations of the ozone kinetics. The work of other research groups is also evaluated.

Structure, Energy, and Vibrational Frequencies of Oxygen Allotropes On (n ≤ 6) in the Covalently Bound and van der Waals Forms: Ab Initio Study at the CCSD(T) Level

“…122,123 The comparison of the kinetic constants was calculated using very accurate PESs (which have a local minimum corresponding to the O 2 ···O complex) does imperfectly agree with the available experimental data, whereas the artificial removal of the local minimum from the PES gives perfect agreement with experimental values. 103,119 In order to elucidate the existence of the complex, we performed a study of the O 3 ···O system at different levels of CCSD(T) theory in different spin states.…”

Towards quantum mechanical description of the unconventional mass-dependent isotope effect in ozone: Resonance recombination in the strong collision approximation

“…7 are populated at room temperature, rendering analysis of zero angular momentum insufficient or even misleading. 7,10,11 This communication focuses on isotopespecific recombination in rotating O 3 .…”

“…16 Calculations are carried out with the three-dimensional PES, V O 3 , already used in previous studies. 9,17 It is a shortrange version of the accurate PES of the ground electronic state, 10 in which shallow van der Waals ͑vdW͒ wells in the asymptotic regions are eliminated and only one oxygen permutation is retained ͑see Ref. 17 for details͒.…”

On collisional energy transfer in recombination and dissociation reactions: A Wiener–Hopf problem and the effect of a near elastic peak

“…[1][2][3][4][5] Our interest in the subject was prompted by studies of ozone whose formation and isotopic effects have been of much recent interest. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] In general, the formation of a molecule AB is described by A + B AB ‫ء‬ , ͑1͒…”