Zero-phonon lines and phonon-sidebands in the 4f 7 6s 2 → 4f 6 5d6s 2 absorption spectrum of Eu atoms isolated in an argon matrix

Abstract

The 4f 7 6s 2 → 4f 6 5d6s 2 absorption spectrum of Eu atoms isolated in an argon matrix shows (a) zero-phonon lines with a half-width ∼ 10 cm −1 and (b) phonon-sidebands due to resonance modes in the Ar : Eu phonon spectrum with h ̷ ω 1 = (12 ± 2) cm −1, h ̷ ω 2 = (26 ± 2) cm −1 and h ̷ ω 3 = (46 ± 4) cm −1 .