Ultrafast dynamics of the lowest-lying neutral states in carbon dioxide

Abstract

We present a study of the ultrafast dissociation dynamics of the lowest-lying electronic excited states in ${\mathrm{CO}}_{2}$ by using ultraviolet (UV) and extreme-ultraviolet (XUV) pulses from high-order harmonic generation. We observe two primary dissociation channels: a direct dissociation channel along the $^{1}{\mathrm{\ensuremath{\Pi}}}_{g}$ electronically excited manifold, and a second channel which results from the mixing of electronic states. The direct dissociation channel is found to have a lifetime which is shorter than our experimental resolution, whereas the second channel has a significantly longer lifetime of nearly 200 fs. In this long-lived channel we observe a beating of the vibrational populations with a period of $\ensuremath{\sim}133$ fs.