Hydrogen migration reactions via low internal energy pathways in aminobenzoic acid dications - UTU Research Portal

A1 Refereed original research article in a scientific journal

Hydrogen migration reactions via low internal energy pathways in aminobenzoic acid dications

Authors: Vetelainen, Onni; Babayan, Morsal; Pihlava, Lassi; Abid, Abdul Rahman; Kivimäki, Antti; Kukk, Edwin; Walsh, Noelle; Urpelainen, Samuli; Björneholm, Olle; Huttula, Marko; Alatalo, Matti; Patanen, Minna; Díaz-Tendero, Sergio

Publisher: ROYAL SOC CHEMISTRY

Publishing place: CAMBRIDGE

Publication year: 2025

Journal: Physical Chemistry Chemical Physics

Journal name in source: PHYSICAL CHEMISTRY CHEMICAL PHYSICS

Journal acronym: PHYS CHEM CHEM PHYS

Volume: 27

Issue: 18

First page : 9884

Last page: 9894

Number of pages: 11

ISSN: 1463-9076

eISSN: 1463-9084

DOI: https://doi.org/10.1039/d5cp00415b

Web address : https://pubs.rsc.org/en/content/articlelanding/2025/cp/d5cp00415b

Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/498736613

Abstract

Hydrogen migration is a ubiquitous phenomenon upon dissociation of organic molecules. Here we investigate the formation of a H₃O+ fragment after core-level photoionization and Auger decay in aminobenzoic acid molecules - a process- that requires the migration of at least two hydrogen atoms. Using photoelectron-photoion coincidence spectroscopy, the formation of a H₃O+ fragment is observed to be more probable in ortho-aminobenzoic acid than in meta- and para-aminobenzoic acid. Energy-resolved Auger electron-photoion coincidences are measured for the ortho-isomer to investigate the internal energy dependence of the fragmentation channels, most notably of those producing H₃O+. The corresponding fragmentation channels and their mechanisms are investigated by exploring the potential energy surface with ab initio quantum chemistry methods and molecular dynamics simulations. Excited-state modeling of dicationic ortho-aminobenzoic acid is used to interpret features in the Auger spectra and identify the electronic states contributing to the signals in the Auger electron photoion coincidence map. We show that populating low-energy excited states of the dication is sufficient to trigger hydrogen migration and produce H₃O+ efficiently.

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Funding information in the publication:
The research leading to these results has been supported by the European Union's Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie I4Future (Grant agreement No. 713606). OV acknowledges the COST Action CA18222 (Attosecond Chemistry). This project was also granted travel funding from CALIPSOPlus from the EU Framework Programme for Research and Innovation Horizon 2020 (Grant agreement No. 730872). ARA acknowledges the Väisälä Fund and the Finnish Academy of Science & Letters. We acknowledge the Research Council of Finland for financial support (including The University of Oulu and Research Council of Finland Profi5 – project 326291 and INTRICat project 341288).