Smallest Organic Tetracation in the Gas Phase: Stability of Multiply Charged Diiodoacetylene Produced in Intense Femtosecond Laser Fields

Coulomb explosion imaging, which is the reconstruction of a molecular structure by measuring three-dimensional momenta atomic ions formed multiply charged cations (MMCs), has been utilized widely. In contrast, intact MMCs, whose properties and reactions are interesting from both fundamental applied scientific perspectives, themselves have little explored to date. This study demonstrates that four-atom molecule diiodoacetylene (DIA) can survive as long-lived species in gas phase after removal four electrons intense femtosecond laser fields. The electron configurations equilibrium structures electronic ground states calculated complete active space self-consistent field (CASSCF) method reveal stability DIA. dissociation energies estimated be 3.01, 3.59, 2.57, 1.82, 1.61 eV for neutral, cation radical, dication, trication tetracation, respectively. A fairly deep potential well suggests DIA tetracation metastable toward dissociation, whereas repulsive pentacation radical confirms its absence mass spectrum. With their sufficiently long lifetimes, minimum number atoms, simple paths, MMCs promising candidates further experimental theoretical investigations ion chemistry.