J. Chem. Phys. 162, 054302 (2025)
Electric-dipole-momentum sensitive Coulomb explosion in doubly ionized CO dimer and trimer: An environmental effect at molecular-scale
C.J. Zhang1,2, R.T. Zhang1,2*, S.C. Yan1,2, L.P. Zou3, S.F. Zhang1,2, Klavs Hansen4, P. Slavicek5, X. Ma1,2
1 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Peoples Republic of China.
2 University of Chinese Academy of Sciences, Beijing 100049, Peoples Republic of China.
3 Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, Peoples Republic of China.
4 Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, 92 Weijin Road, Tianjin 300072, Peoples Republic of China.
5 University of Chemistry and Technology, Department of Physical Chemistry, Technická 5,16628 Prague 6, Czech Republic.
* zhangrt@impcas.ac.cn
Abstract
Molecular clusters are aggregates of molecules weakly bound by the van der Waals force between molecules. Removing one electron from each constitutive molecule results in van der Waals bond cleavages through Coulomb explosion. This provides an ideal prototype to further study the environmental effects played by one fragmented ion on the other one at the molecular scale. Here, we report an experimental measurement of the two-body Coulomb explosion of (CO)2+ and (CO)2+ prodced in a 40 keV Ar2+ double-electron capture collision with CO dimer and trimer. Accurate reaction pathways are identified with the advanced ion-ion coincidence and momentum-imaging techniques. The measured kinetic energy release deviates from the calculated results based on the reciprocal of internuclear distance (i.e., Coulomb interaction only), and which therefore requires the inclusion of rotational energy of CO+ initiated by molecular electric-dipole-momentum. Molecular dynamics simulations reveal that the separation defining the rotational energy takes place within a few hundred fs after the onset of dissociation. This molecular-scale environmental effect significantly brings calculations and measurements of the kinetic energy release into agreement.
