Probing the Influence
of Size and Composition on the
Photoelectron Spectra of Cadmium Chalcogenide Cluster Dianions
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Abstract
We have synthesized a series of compounds comprising
the halide-free
cadmium chalcogenide cluster dianions [Cd<sub>8</sub>Se(SePh)<sub>16</sub>]<sup>2–</sup>, [Cd<sub>17</sub>Se<sub>4</sub>(SePh)<sub>28</sub>]<sup>2–</sup>, [Cd<sub>17</sub>S<sub>4</sub>(SPh)<sub>28</sub>]<sup>2–</sup>, and [Cd<sub>17</sub>Se<sub>4</sub>(SPh)<sub>28</sub>]<sup>2–</sup> to study their size- and
composition-dependent electronic properties free of matrix effects.
Toward this end, photoelectron spectra of the isolated dianions electrosprayed
from solution were recorded at several detachment photon energies.
Together with quantum chemical calculations, these data reveal a systematic
correlation between electronic properties such as electron affinities
or repulsive Coulomb barriers and the composition/size of these semiconducting
cluster complexes. We infer that the excess negative charges are localized
at the apical sites of these near-tetrahedral molecules