Atomic and molecular physics

Interaction of He$^{2+}$ ions with heterocyclic cyclodialanine molecules

A. A. Basalaev^a, V. V. Kuz'michev^a, M. N. Panov^a, A. V. Petrov^b, K. V. Simon^a, O. V. Smirnov<sup>a

a</sup> Ioffe Institute, St. Petersburg, Russia
^b Institute of Chemistry, St. Petersburg State University, St. Petersburg, Russia

Abstract: Mass spectrometric analysis of alpha-particle-induced fragmentation of heterocyclic molecules of the dipeptide cyclo(Ala-ala) (C$_6$H$_{10}$N$_2$O$_2$, 3,6-Dimethylpiperazine-2,5-dione) has been performed. Relative cross sections of various elementary processes occurring during single collisions of cyclo(Ala-ala) with ions have been measured for the first time. The geometry of molecules and singly charged ions, as well as reaction pathways of various experimentally observed fragmentation channels of these ions, have been calculated using the multiconfigurational self-consistent field method in the complete active space (CASSCF). The optimized geometry of molecules and singly charged ions, as well as their total energy, have been calculated using the density functional theory (DFT).

Keywords: electron capture, dipeptides, molecular ion fragmentation, mass spectrometry, DFT, CASSCF method.

Received: 23.08.2024
Revised: 25.10.2024
Accepted: 29.11.2024

DOI: 10.61011/JTF.2025.04.60001.259-24

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