Laser induced production of excited states of PH and PH2 from phosphine

Luminescence from the à excited states of PH and PH2 has been observed following irradiation of PH3 with an ArF excimer laser (193.3 nm). Initial vibrational distributions in PH2(Ã) have been determined. The large population in v′2=0 may be understood in terms of the Franck–Condon principle in view of the similarities in geometry of PH3(Ã) and PH2(Ã). While formation of PH2(Ã) is linear in laser intensity, corresponding to a simple one-photon dissociation process, PH(A) is produced in a two-photon process. Lifetimes and cross sections for quenching by PH3 have been measured for vibrational levels of PH2(Ã) and for spin–orbit subcomponents of PH(A). The quantum yield for photochemical production of PH2(Ã) at low laser intensities has been measured to be 0.014±0.006.