Mass spectrometric study of the structures and ionization potential of LinI (n = 2, 4, 6) clusters

Abstract

We report a combined experimental and theoretical investigation of small heterogeneous clusters of lithium iodide. Apparatus based on magnetic sector instrument, where Knudsen cell is placed into the ionization chamber, provides suitable conditions for the detection of both the ionic and neutral components of Li_nI (n = 2, 4, 6) clusters. The clusters Li₄I and Li₆I were detected experimentally for the first time. Ionization potentials determined by the electron impact ionization mass spectrometry were (4.69 ± 0.25) eV for Li₂I, (4.86 ± 0.25) eV for Li₄I and (4.96 ± 0.25) eV for Li₆I. The ionization potential of Li₂I corresponds to previous experimental data obtained by thermal ionization mass spectrometry. The first theoretical data of the ionization potential and structure of the above mentioned clusters are presented in this work. A comparison with the experimental ionization potentials provides evidence for the theoretically calculated geometrical structures of the small heterogeneous clusters of lithium iodide.