A study of the ground electronic states of the isoelectronic ions PF+ and NCI+ by vacuum ultraviolet photoelectron spectroscopy

Abstract

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 r_e, 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.