A study of the ground electronic states of the isoelectronic ions PF+ and NCI+ by vacuum ultraviolet photoelectron spectroscopy
NCI(a1Δ), prepared from the CI + N3 reaction, and PF(X3Σ–), prepared as a secondary product of the F + PH3 reaction, have been investigated with vacuum ultraviolet photoelectron spectroscopy. The adiabatic ionization energy for the process NCI+(X2Π)â†� NCI(a1Δ) was measured as 9.69 ± 0.02 eV and this has led to a determination of the first adiabatic ionization energy of NCI(X3Σ–) of 10.84 ± 0.02 eV. The first adiabatic ionization energy of PF(X3Σ–) was measured as 9.60 ± 0.01 eV. Spectroscopic constants, e and re, in the ground 2Π state of the ions were determined as 1160 ± 30 cm–1 and 1.489 ± 0.005 Å for NCI+ and 1030 ± 30 cm–1 and 1.498 ± 0.005 Å for PF+, respectively. Assignments of the observed photoelectron bands have been supported by ab initio SCF-CI molecular-orbital calculations.