Einstein A-values and oscillator strengths of the A2П–X2Σ+ system of CP

Abstract

Line strengths for bands of the A2П–X2Σ+ transition of CP, including the effect of rotation on the vibrational wavefunctions (the Herman–Wallis effect), have been calculated using Western׳s PGOPHER program and Le Roy׳s LEVEL program. The potential energy functions for the A2П and X2Σ+ state were computed using spectroscopic constants obtained from high resolution spectra. The RKR potentials of the two states, and the electronic transition dipole moments of this transition calculated in a recent ab initio study have been used in Le Roy׳s LEVEL program to produce transition dipole moment matrix elements. The matrix elements have been converted from Hund׳s case (b) to (a), and then used in PGOPHER to generate a line list containing observed and calculated wavenumbers, Einstein A coefficients and f-values for 75 bands with v=0–8 for both states. The Einstein A coefficients have been used to compute radiative lifetimes for v=0–5 in the A2П state. The line list may be useful for computing the molecular opacities of CP needed to simulate the spectra of stellar and substellar sources.