The Vacuum Ultraviolet Spectrum of ICI

Abstract

The absorption spectrum of iodine chloride has been photographed in the high orders of a 10.7 m concave grating spectrograph in the region 1900–1220 Å. A number of band systems which correspond to Rydberg transitions have been obtained. In addition an extensive band system with closely spaced bands degraded to longer wavelengths has been observed in the region 1660–1580 Å. Among the Rydberg systems, 12 series have been found to converge to 81 362 ± 80 cm−1 which very likely represents the ionization potential of the molecule leading to the 2Π3/2 state of the molecular ion. They are due to transitions from the ground state to states arising from the configurations (σ2π4π32Π3/2)ns σ, (2Π3/2)np σ, (2Π3/2)np π, (2Π3/2)nd σ, (2Π3/2)nd π, (2Π3/2)nd δ, (2Π3/2)nf σ, (2Π3/2)nf π, and (2Π3/2)nf δ where n takes the running values 6, 7, 8, … for the first three configurations, 5, 6, 7, … for the next three configurations, and 4, 5, 6, … for the last three configurations. The first few numbers of 11 similar series corresponding to the transitions to the states involving the (σ2π4π32Π1/2) core have been identified and the ionization of these series is estimated to be at 85 996 ± 80 cm−1.