Charge Transfer, Complexes Formation and Furan Fragmentation Induced by Collisions with Low-Energy Helium Cations

Abstract

The present work focuses on unraveling the collisional processes leading to the fragmentation of the gas-phase furan molecules under the He+ and He2+ cations impact in the energy range 5–2000 eV. The presence of different mechanisms was identified by the analysis of the optical fragmentation spectra measured using the collision-induced emission spectroscopy (CIES) in conjunction with the ab initio calculations. The measurements of the fragmentation spectra of furan were performed at the different kinetic energies of both cations. In consequence, several excited products were identified by their luminescence. Among them, the emission of helium atoms excited to the 1s4d 1D2, 3D1,2,3 states was recorded. The structure of the furan molecule lacks an He atom. Therefore, observation of its emission lines is spectroscopic evidence of an impact reaction occurring via relocation of the electronic charge between interacting entities. Moreover, the recorded spectra revealed significant variations of relative band intensities of the products along with the change of the projectile charge and its velocity. In particular, at lower velocities of He+, the relative cross-sections of dissociation products have prominent resonance-like maxima. In order to elucidate the experimental results, the calculations have been performed by using a high level of quantum chemistry methods. The calculations showed that in both impact systems two collisional processes preceded fragmentation. The first one is an electron transfer from furan molecules to cations that leads to the neutralization and further excitation of the cations. The second mechanism starts from the formation of the He−C4H4O+/2+ temporary clusters before decomposition, and it is responsible for the appearance of the narrow resonances in the relative cross-section curves.

Carboxylation Enhances Fragmentation of Furan upon Resonant Electron Attachment

“… 29 Moreover, several examples of chemical intramolecular mechanisms of hydrogen migration in the charged state of the furan and its substituents were observed. 30 , 31 Finally, substitution can affect the chemical and biochemical interaction of the ring structures. 32 , 33 It is therefore interesting to study how substituion of the ring influences the interaction with low energy electrons, particularly for 2FA with several important applications.…”

Neutral Dissociation of Pyridine Evoked by Irradiation of Ionized Atomic and Molecular Hydrogen Beams

“…Our luminescence fragmentation spectra may also be compared with the emission spectra measured in collisions involving other heterocyclic biomolecules. In the series of works regarding the cation- [ 28 , 31 ] electron- [ 44 , 45 ], and photon-induced [ 53 , 54 , 55 , 56 , 57 , 58 ] fragmentation of isoxazole, pyrrole, tetrahydrofuran, pyrimidine, five- and six-membered heterocyclic molecules, we observed complex fragmentation spectra suggesting significant disintegration of their rings. The electron-induced fragmentation processes of larger biomolecules also showed similar nature.…”

“…Focused ion beams are employed for etching, deposition, and direct-write lithography and fabrication technology [ 13 , 14 ] and for sample imaging in ion microscopes [ 15 , 16 , 17 ]. However, the most intense studies are performed to elucidate the ion-induced alterations to structure blocks of living cells, mainly the DNA/RNA molecules [ 18 , 19 , 20 , 21 , 22 ] and their analogs [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. The reason is that the ionic beams are effectively applied in hadrontherapy to irradiate the cancerous cells [ 33 , 34 , 35 ].…”

“…The interaction of ions with biological molecules in the gas phase leads to ionization, excitation, charge transfer, complex formation, and dissociation processes that produce neutral and ionic products [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. The mass spectrometric methods are developed to probe the charged entities [ 22 , 39 ], as well as to study neutral fragments in high-Rydberg states but without identifying their final states [ 40 , 41 ].…”

“…Although fluorescence spectroscopy is a powerful technique to probe the reaction intermediates and fundamental properties of atoms [ 59 , 60 , 61 ] molecules [ 43 , 62 , 63 ], and materials [ 64 ], it has been rarely used to explore ion-induced neutral dissociation of polyatomic targets [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 65 ]. One of such objects is pyridine C5H5N—the simplest six-membered nitrogen-containing heterocycle compound.…”