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

Abstract

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 N 2 and CO and for carbon 1s ionization of CO show evidence of this effect.

Energy Transfer into Molecular Vibrations and Rotations by Recoil in Inner-Shell Photoemission

“…However, carbon 1s ionization of CO results in a shrinkage of the CO bond length between the neutral molecule and the core-ionized molecule [12]. Because of this shrinkage, it is predicted that Coriolis coupling will lead to a transfer of energy from the vibrational mode to the rotational mode [13]. Until now, this predicted effect has not been observed.…”

“…The equilibrium bond length of CO shortens upon core ionization, which leads to a lower moment of inertia and, hence, to a higher rotational energy for a given angular momentum. This increase in rotational energy is taken from the vibrational excitation through Coriolis coupling [13]. In CO, the bond length shortens from 1.128 to 1.079 Å [8], which results in a Coriolis-induced increase in the rotational recoil energy by 9.3% and a decrease by the same amount (and percentage of 18.6%) in the vibrational recoil energy.…”