Discrete Structure in the Spectrum of Sodium Iodide Vapor

The fluctuation bands of NaI are shown to be intensity alternations in a resolved band system. The fluctuations, spaced by about 300 cm−1, are associated primarily with the ground-state vibrational spacing; the band structure spacing of 36 cm−1 is probably to be associated with the vibrational frequency of the excited state. The discrete line spectrum occurs without any break from 2945 to 5400 Å. From the low-wavelength limit a dissociation energy for the ground state, D0 = (26 343 ± 232) cm−1, is derived.