The absorption spectrum of diatomic phosphorus between 1370 and 600 Å

Abstract

Nine Rydberg series have been observed in the far ultraviolet absorption spectrum of P₂. Four of these converge to the.(5σ_g)²(2π_u)³, 2II_u (inv.) state of the ion which is established as being the ground state; four to the low-lying ...(5σ_g) (2π_u)⁴, A²Ʃ_g+ state and one to a newly identified (5σ_g) (2π_u)3 2πg, F²Ʃ⁺_u state. The first ionization potential is found to be 85 229 ± 15 cm-1 (10.567 ± 0.002eV), which is the limit corresponding to the upper component (2II1/2 ) of the inverted X 2II_u state. The other limits are observed at 87 179 + 2cm^-1 (A ²Ʃ⁺_g) and 125 225 ± 10cm^-1 (F² Ʃ⁺_u). The series have been interpreted in terms of molecular orbitals and are found to involve excitation of nsσ_g,ndσ_g, ndπ_g and ndδ_g for the X ²II_ucore; npπ_u, nfσ_u, and nfπ_u for the A ²Ʃ⁺_g core and for the A²Ʃ⁺_u core. The evaluation and identification of the series limits enables the relative positions of the states of P⁺₂ to be established. The dissociation energy of P⁺₂ is estimated to be 4.98 ± 0.01eV.