Coulomb-explosion inversion: reconstruction of molecular structure through clustering and Newtonian mechanics

Coulomb-explosion imaging (CEI) is a promising method for imaging nuclear geometries and recent developments have led to the possibility of making time-resolved CEI images of molecular processes [1]. However, determining the initial geometry from the measured momenta is not straightforward due to non-Coulombic potentials, non-uniqueness of the inversion, and for strong-field ionization charge-up timescales [2]. Various approaches to these theoretical issues have been attempted, such as backwards integration of the final momentum and tabular look-up and comparison to simulated results [3], yet these methods have complications involving the degeneracy of the inversion. The process of Coulomb explosion can result in multiple initial conditions that map to the same final momentum, yet the methods previously mentioned only result in one solution. We instead use a brute force approach of partitioning the final energy into initial degrees of freedom. We then propagate the numerous matching initial conditions using Newtonian mechanics and Coulombic potentials. We have found that this procedure can address non-uniqueness and provides sufficient solutions for the inversion problem. We acknowledge the grant DE-FG02-86ER13491for funding this work.



[1] Boll, R., Schäfer, J.M., Richard, B. et al. Nat. Phys. 18, 423-428 (2022).

[2] A. M. Sayler, E. Eckner, J. McKenna, B. D. Esry, K. D. Carnes, I. Ben-Itzhak, and G. G. Paulus. Phys. Rev. A. 97, 033412 (2018).

[3] Ramadhan, Ali. “Molecular movies and geometry reconstruction using Coulomb explosion imaging”, Masters Thesis (2017).