MULTIPHOTON IONIZATION SPECTROSCOPY OF PHOSPHINE

New insight into the Rydberg state spectroscopy of the phosphine molecule has been afforded by analysis of the resonance enhanced multiphoton ionization spectra of PH3 and PD3 under both bulk and beam conditions. Similarities with the well-documented vertical electronic spectrum of the ammonia molecule are clearly evident. Parallel studies of MPI resonances attributable to PH(b 1Σ+) radicals and to P atoms produced via multiphoton excitation of phosphine emphasise the extent to which the electronic spectrum of phosphine (and of the Rydberg states of the PH radical) may be understood by visualising these molecular species in terms of a P atom, ‘dressed’ with the relevant number of hydrogen atoms. The previously reported MPI of PH (b 1Σ+) radicals, resonantly enhanced at the two photon energy by the 3Σ+ Rydberg state with electronic configuration KL (3pσ)2(3pπ)1(4pπ)1, is observed to exhibit a rotational level dependent branching between P+ and PH+ ion products. This unexpected finding can be explained by i...