Fragmentation dynamics of meso-tetraphenyl iron (III) porphyrin chloride dication under energy control

Abstract

Meso-tetraphenyl iron (III) porphyrin chloride dications (FeTPPCl) were prepared in collisions with F and H at 3 keV. The dominant fragmentation channels were observed to involve the loss of the Cl atom and the successive loss of neutral phenyl groups for both collisional systems. The mass spectra in correlation with the deposited excitation energy distributions of the parent ions for the main fragmentation channels were measured by using the collision induced dissociation under energy control method. The global excitation energy distribution was found to be shifted to lower energies in collisions with H compared to collisions with F showing a noteworthy change of the excitation energy window using different projectile ions. Partial excitation energy distributions of the parent ions FeTPPCl were obtained for each fragmentation group. In a theoretical work, we have calculated the dissociation energies for the loss of one and two phenyl groups, including phenyl and (phenyl ± H). The energy barrier for the hydrogen atom transfer during the loss of (phenyl-H) has been also calculated. The measured energy difference for the successive loss of two phenyl groups was compared with the theoretical values.

Roadmap on dynamics of molecules and clusters in the gas phase

“…Proton transfer was also observed between sugar-and base-part of thymidine in competition with the expected glycosidic bond cleavage [105]. The above-mentioned unexpected dissociation pathways are expected to be found for many other systems, for which the reactivity is triggered by the keV ion impact [106].…”

“…This resonant charge transfer can occur at large distance in the case of multiply charged ion collisions, and therefore, multiple electron captures are usually observed leading to the formation of "cold" multiply charged molecular cations [104]. Thus varying the charge state of the projectile, the excitation energy associated with keV ion collisions ranges from few eV [105] to few 10s of eV [106]. When the ion trajectory is penetrating the molecular system and as the projectile is a massive particle, energy can be deposited both on the electrons by friction with the electronic cloud, the so-called electronic energy loss, and on the nuclei in binary collisions, the so-called nuclear energy loss.…”