Unusual Quartet‐Doublet Phosphorescence from the Phosphaethynyl Radical, CP

Abstract

We report the first detection of phosphorescence from the phosphaethynyl radical. This rare instance of quartet‐doublet emission, studied here in solid argon, is presumably promoted by efficient intersystem crossing from the originally photoexcited doublet (B2Σ+) to the adjacent second quartet state, 14Δ. Vibronic progressions were traced for the a4Σ+‐X2Σ+ and a4Σ+‐A2Пi systems from their origins up to (v′=0)→(v′′=5) and (v′=0)→(v′′=2) bands, respectively. The measured phosphorescence lifetime is 108 ± 3 ms.