Rate coefficients of the formation reactions of ¹⁸O-bearing ozone (top panel) and ¹⁷O-bearing ozone (bottom panel) relative to that of O₃ (﹩={k}_{{\rm{O}}+{{\rm{O}}}_{2}+{\rm{M}}}﹩) as a function of temperature. The solid red lines represent the rate coefficients of the reactions between O and O¹⁸O (or O¹⁷O), and the solid orange lines represent those of the reactions between ¹⁸O (or ¹⁷O) and O₂. The dashed lines represent the branching ratios of the production of symmetric and asymmetric ozone through the reactions between O and O¹⁸O (or O¹⁷O). The dotted black line represents the value corresponding to no isotopic fractionation.