Table 2. (Top) Orbital energies of NaI (aq.) extracted from the vacuum/liquid-interface-sensitive measurements reported in this study (180/198 eV photon energies), and from crystalline NaI.113 (Bottom) Orbital energies of NaI (aq.) inferred from the bulk-sensitive measurements reported in this study.

	Peak	BE [eV]
		0.5 M	8.0 M	ΔE	NaI crystal
Interface	I– 5p3/2	7.83 ± 0.04	7.72 ± 0.05	–0.11 ± 0.07	—
	I– 5p1/2	8.70 ± 0.11	8.67 ± 0.05	–0.03 ± 0.12	—
	Na+ 2p	35.39 ± 0.04	35.41 ± 0.04	+0.02 ± 0.06	29.29
	I– 4d5/2	53.84 ± 0.04	53.74 ± 0.04	–0.10 ± 0.06	47.68
	I– 4d3/2	55.52 ± 0.04	55.44 ± 0.06	–0.08 ± 0.07	49.35
Bulk	I– 5p3/2	7.82 ± 0.04	7.71 ± 0.04	–0.11 ± 0.06	—
	I– 5p1/2	8.71 ± 0.10	8.67 ± 0.04	–0.04 ± 0.11	—
	I– 5s	Not detectable	19.6 ± 0.4	Not detectable	11.21
	Na+ 2p	35.44 ± 0.04	35.41 ± 0.04	–0.03 ± 0.06	29.29
	I– 4d5/2	53.89 ± 0.04	53.74 ± 0.04	–0.15 ± 0.06	47.68
	I– 4d3/2	55.57 ± 0.04	55.44 ± 0.04	–0.13 ± 0.06	49.35