Supplement materials

Initial geometries and optimized geometries of PtInˉ/PtIn (n=2−5) with different spin multiplicities; the XYZ axis used to construct anion's MOs; simulated DOS spectra with explicit MO plots; the excited states of the neutrals, the DOS stick spectra in comparison with the experimental ones; detailed display of PtI2ˉ MOs; simulated absorption spectra; an amplified PE spectrum of PtI5ˉ in the eBE=2.0 to 3.9 eV region; RESP charge distribution of the anions and neutrals upon vertical detachment