Laser photoelectron spectrometry of PO−, PH−, and PH−2

Abstract

Fixed‐frequency laser photoelectron spectrometry has been used to study the ions PO⁻, PH⁻, and PH⁻₂. The electron affinities of PO, PH, and PH₂ were determined to be (1.092±0.010), (1.028±0.010), and (1.271±0.010) eV, respectively. A bound excited state (ã ¹Δ) of PO⁻ was observed with a term energy of (0.556±0.010) eV. The vibrational frequencies of X̃ ³Σ⁻ PO⁻, ã ¹Δ PO⁻, X̃ ²Π PH⁻, and ²B₁ PH₂ (ν₁) were found to be (1000±70), (1020±80), (2230±100), and (2270±80) cm⁻¹, respectively. A Franck–Condon factor analysis of the PO⁻ and PH⁻ spectra gave the equilibrium internuclear separations r_e(X̃ ³Σ⁻ PO⁻) = (1.540±0.010) Å and 1.414⩾r_e(X̃ ²Π PH⁻) ⩾1.400 Å. The geometries of ¹A₁ PH⁻₂ and ²B₁ PH₂ were found to be nearly the same. The PH⁻ photoelectron spectrum includes transitions to the PH X̃ ³Σ⁻ and ã ¹Δ states, allowing determination of the intercombination separation of (0.950±0.010) eV.