Photoionization mass spectrometric study and <i>a</i> <i>b</i> <i>i</i> <i>n</i> <i>i</i> <i>t</i> <i>i</i> <i>o</i> calculations of ionization and bonding in P–H compounds; heats of formation, bond energies, and the 3<i>B</i>1–1<i>A</i>1 separation in PH+2

Abstract

The ion yield curves of PH+3, PH+2, and PH+ from photoionization of PH3 have been measured. The free radical PH2 has been generated by pyrolysis, and the ion yield curve of PH+2 (PH2) determined. These measurements yield directly I.P. (PH3)=9.870±0.002 eV, and I.P. (PH2)=9.824±0.002 eV. In addition, we deduce D0 (H2P–H)=82.46±0.46 kcal/mol, D0 (HP–H)=74.2±2 kcal/mol, D0 (P–H)=70.5±2 kcal/mol, I.P. (PH)=10.18±0.1 eV, and other thermochemically related quantities. The ionization energies of PH, PH2, and PH3 are computed by ab initio molecular orbital methods to fourth order in Mo/ller–Plesset theory, and are found to be in good agreement with experiment. The ground state of PH+2 is inferred to be 1A1, with the 3B1 state higher by ≥0.71 eV. This ordering is the reverse of that in CH2 and NH+2.