Nuclear Spin of Phosphorus from the Band Spectrum

Abstract

THE extensive band system of P₂ in the ultraviolet is easily produced with considerable intensity by an uncondensed discharge through pure phosphorus vapour contained in a quartz tube. Regularities in the frequencies of the band heads were first found by Geuter, but the correct quantum designation of the bands has only recently been established by the work of Jakowlewa¹ on the absorption and fluorescence of the more refrangible part of this system. Two years ago, Herzberg reported, in a letter to NATURE, that a sudden breaking off occurs in the band progressions associated with various upper vibrational levels (at σ′ = II with the present assignment of vibrational quantum numbers), which can only be attributed to predissociation.² Herzberg also found that the rotational lines of the bands of highest observed ½′ stop suddenly, as was to be expected in consequence of the predissociation.