Coriolis interaction and the division of energy between vibrational and rotational excitation induced by photoelectron recoil

The effect of the Coriolis interaction upon the sharing of energy between rotational and vibrational excitation during an electronic transition is considered with particular emphasis on recoil-induced excitation during photoionization. If there is a large change in equilibrium bond length upon ionization, then Coriolis coupling leads to a significant transfer of energy between rotational and vibrational excitation. Experimental results for valence ionization of ${\mathrm{N}}_2$ and CO and for carbon $1s$ ionization of CO show evidence of this effect.

Figure 1

Intensity ratios $(v=1)/(v=0)$ for carbon $1s$ ionization of CO plotted against the momentum of the photoelectron. Open circles represent the experimental data from Ref. [13]. The dashed line represents a semiempirical fit to the data, and the dotted curve represents a theoretical calculation of the ratios [13]. For both curves there has been no correction for the Coriolis interaction. The solid curve shows the semiempirical fit with inclusion of the Coriolis correction.