A new electronic transition of the PN molecule

Abstract

A transition accidentally observed at high dispersion in absorption spectra and at low resolution in emission spectra is shown to be due to the PN molecule. A vibrational classification is given. The transition involves the already known ground state X 1 Sigma + and a new excited state which is thought to be a 1 Sigma + state for which twelve vibrational levels are observed. Anomalous vibrational separations are detected for this state.