Ozone ultraviolet photolysis. VI. The ultraviolet spectrum

The ozone ultraviolet spectrum has been re‐examined at low temperature to clarify features of photochemical interest. The origin of the system is a diffuse band at 28 450 cm⁻¹, the long wavelength limit of band structure in the cold spectrum. The bands toward higher frequencies are identified as sequences of the upper state bending (333 cm⁻¹) and symmetrical stretching (600 cm⁻¹) modes. This band structure converges to a limit near 32 400 cm⁻¹, consistent with the energy required to form O(¹D) plus O₂(¹Δ). Both the shading of the bands and sequences which appear suggest that the Huggins bands are that part of the Hartley‐Huggins system which lies below the dissociation limit, the system being a single transition ${}^1{B}_2{\mathrm{\leftarrow \; X\hspace{0.17em}}}^1{A}_1$ . The component of the continuum due to excitation of the ${\nu }_{010}^{″}$ bending mode is shown to be similar to that arising from the ${\nu }_{000}^{″}$ ground state, except for a shift toward lower energy equal to the vibrational excitation energy. A rationale for predicting the effect of temperature on the shape of the continuum is presented.