Isotope shift studies of the ultra-violet and visible bands of P¹⁶O and P¹⁸O

Abstract

The spectra of P¹⁶O and P¹⁸O were excited in sealed discharge tubes containing neon (2-3 mm. pressure), oxygen gas enriched to 65 per cent. of ¹⁸O and trace amounts of phosphorus vapour and photographed on a 3 m. grating spectrograph at a dispersion of 2.5 Å/mm. Isotope shift studies in the β-bands confirmed the earlier vibrational scheme of Curryet al. and showed conclusively that the red as well as the violet degraded bands belonged to the same β-system. The present studies of isotope shifts also confirmed the vibrational assignments of the extensive ultraviolet bands involving the ²∑^--X²Π transition and the γ-bands (A²∑⁺-X²Π). In the case of the visible bands, they provided evidence for the first time that the bands at 5585Å, 5962Å and 6385Å belonged to one system and involved 0-0, 0–1 and 0–2 transitions respectively.