skip to main content

Title: Isomeric signatures in the fragmentation of pyridazine and pyrimidine induced by fast ion impact

We present fast proton impact induced fragmentations of pyrimidine and pyridazine as an experimental resource to investigate isomeric signatures. Major isomeric imprints are identified for few fragment ions and differences of more than an order of magnitude for the cross sections of fragments of the same mass were measured. The observation of the molecular structure of these isomers gives no apparent indication for the reasons for such substantial differences. It is verified that the simple displacement of the position of one nitrogen atom strongly inhibits or favors the production of some ionic fragment species. The dependency of the fragmentation cross sections on the proton impact energy, investigated by means of time of flight mass spectroscopy and of a model calculation based in first order perturbation theory, allows us to disentangle the complex collision dynamics of the ionic fragments. The proton-induced fragmentation discriminates rather directly the association between a molecular orbital ionization and the fragment-ions creation and abundance, as well as how the redistribution of the energy imparted to the molecules takes place, triggering not only single but also double vacancy and leads to specific fragmentation pathways.
Authors:
; ;  [1]
  1. Instituto de FĂ­sica, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro, RJ (Brazil)
Publication Date:
OSTI Identifier:
22493957
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 74 ATOMIC AND MOLECULAR PHYSICS; ATOMS; CROSS SECTIONS; FRAGMENTATION; HYDROGEN IONS; IONIZATION; ION-MOLECULE COLLISIONS; ISOMERS; MASS SPECTROSCOPY; MOLECULAR ORBITAL METHOD; MOLECULAR STRUCTURE; MOLECULES; NITROGEN; PERTURBATION THEORY; PROTONS; PYRIDAZINES; PYRIMIDINES; TIME-OF-FLIGHT METHOD; VACANCIES