The strongest absorptions with the lower-level excitation potentials \chi _ { low } < 1 eV are found to be split in the high-resolution optical spectra of the post-AGB star V354 Lac taken in 2007–2008 with the 6-m telescope of the Special Astrophysical Observatory .
Main atmospheric parameters , T _ { eff } =5650 K , \log g =0.2 , \xi _ { t } =5.0 km/s , and the abundances of 22 chemical elements in the star ’ s atmosphere are found .
The excess of the s -process metals ( Ba , La , Ce , Nd ) in the star ’ s atmosphere is partly due to the splitting of strong lines of the ions of these metals .
The peculiarities of the spectrum in the wavelength interval containing the LiI \lambda 6707 Ã line can be naturally explained only by taking the overabundances of the CeII and SmII heavy-metal ions into account .
The best agreement with the synthetic spectrum is achieved assuming \varepsilon ( LiI ) =2.0 , \varepsilon ( CeII ) =3.2 , and \varepsilon ( SmII ) =2.7 .
The velocity field both in the atmosphere and in the circumstellar envelope of V354 Lac remained stationary throughout the last 15 years of our observations .