Improvement of the Spectroscopic Constants of the PF(A³Π) State and Assignment of the PF(A–X) Transition Dipole Function

Author： Nizamov B. Setser D.W.

Publisher： Academic Press

ISSN： 0022-2852

Source： Journal of Molecular Spectroscopy, Vol.206, Iss.1, 2001-03, pp. : 53-61

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Abstract

High-resolution laser-excitation spectra were acquired for the v′=3–7 levels of the PF(A³Π_0,1,2←X³Σ^-) transition from PF(X³Σ^-) molecules generated in a discharge flow reactor. These results were combined with lower resolution excitation spectra for the v′=8–11 levels and with existing high-resolution data in the literature for v′=0 and 1 to assign improved spectroscopic constants for PF(A³Π_0,1,2). The abnormal vibrational energy level spacings for all spin components of the PF(A³Π) state are evidence for a homogeneous interaction with another ³Π state. The Λ-doublet separation in the PF(³Π₀) substate increases with vibrational level, which is taken as evidence for interaction with the PF(b¹Σ⁺) state. Laser-induced fluorescence spectra from individual v′=0–5 levels were used to obtain vibrational band intensities of the A–X transition. The strong dependence of the transition dipole on the r-centroid is consistent with the reduction in the radiative lifetimes with increasing v′ level. The similarity between the isovalent PF(A³Π) and SO(A³Π) states is noted and the bond dissociation energy of PF(X³Σ^-) is discussed.