Photodetachment of thermally relaxed CO3−

Abstract

The absolute photodetachment cross section $\sigma$ and the solar detachment rate of ground electronic and vibrational energy state of C${\mathrm{O}}_3^{-}$ have been determined by using electron-detecting-drift-tube method. The C${\mathrm{O}}_3^{-}$ ion is identified by mass and mobility measurements. The cross section is measured with the use of 19 color filters. By fitting data with a least-squares program, it is found that $\sigma \left(\lambda \right)=[a_1+a_2{\lambda }^{\prime }+a_3{\lambda }^{\prime 2}+a_4{\lambda }^{\prime 3}]\theta ({\lambda }_0-\lambda )$, where ${\lambda }_0=459\mathrm{}$ nm (2.69 eV), ${\lambda }^{\prime }=(\lambda -385)$ nm, $a_1=(1.21\mathrm{}\pm 0.32)\times {10}^{-19\mathrm{}}$ ${\mathrm{cm}}^2$, $a_2=(-3.61\mathrm{}\pm 1.68)\times {10}^{-21\mathrm{}}$ ${\mathrm{cm}}^2$/nm, $a_3=(1.62\mathrm{}\pm 0.23)\times {10}^{-22\mathrm{}}$ ${\mathrm{cm}}^2$/${\mathrm{nm}}^2$, and $a_4=(2.00\mathrm{}\pm 0.37)\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$/${\mathrm{nm}}^3$; $\theta$ is the Heaviside step function. The threshold energy of ${2.69}_{-0.14\mathrm{}}^{+0.07\mathrm{}}$ eV is identified as the electron affinity of C${\mathrm{O}}_3$. The solar photodetachment rate is 0.022 ± 0.003 ${\sec }^{-1\mathrm{}}$. The upper bound for the binding energy of C${\mathrm{O}}_3$ is determined as 0.6 ± 0.1 eV.