Anisotropy parameters from shapes of ion-ion correlation features of fragmenting molecules

Emelie Olsson; Måns Wallner; Richard J Squibb; Veronica Ideböhn; Marco Parriani; Michael A Parkes; Stephen D Price; John H D Eland; Raimund Feifel

doi:10.1038/s41598-024-80014-z

Anisotropy parameters from shapes of ion-ion correlation features of fragmenting molecules

Sci Rep. 2024 Nov 20;14(1):28766. doi: 10.1038/s41598-024-80014-z.

Authors

Emelie Olsson¹, Måns Wallner¹, Richard J Squibb¹, Veronica Ideböhn¹, Marco Parriani^{1

2}, Michael A Parkes³, Stephen D Price³, John H D Eland⁴, Raimund Feifel⁵

Affiliations

¹ Department of Physics, University of Gothenburg, Origovägen 6B, Gothenburg, 412 58, Sweden.
² Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, Perugia, 06125, Italy.
³ Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
⁴ Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, OX1 3QZ, UK.
⁵ Department of Physics, University of Gothenburg, Origovägen 6B, Gothenburg, 412 58, Sweden. raimund.feifel@physics.gu.se.

Abstract

When a molecule loses two electrons, Coulomb repulsion makes the resulting doubly charged system likely to fragment into two singly charged ions. These monocations can be detected in a correlated fashion using multiplex time-of-flight spectroscopy. The island shapes in the ion-ion coincidence maps derived from such two-body dissociations contain detailed information on the physical processes underlying the fragmentation. Here, a simple method is presented where a fit function is used to determine the anisotropy parameter β of the molecular distribution from the peak shape of the time-of-flight difference of the two ions. The validity of the method is demonstrated by performing fits to simulated peak shapes, recovering the β value of the input angular distribution, and by comparison of experimental peak shapes to β values known from the literature.