Absorption spectrum of Ca i in the 1580–2090-Å region

Abstract

The absorption spectra of Ca I in the wavelength ranges ∾ 1550–1770 Å and ∾ 2020–2090 Å have been photographed in the third order of a 6.6-m spectrograph. Calcium vapor was produced by heating calcium metal in an evacuable King-furnace system with a hot zone 122 cm long. The 4s²¹S₀–4s n p¹P₁^° series has been extended to n = 79, which corresponds to 46 new 4s np¹P₁^° levels and leads to an improved value for the ionization potential of Ca i. More than 230 doubly excited levels have been observed in the vacuum region, of which over 140 correspond to new levels. All but five of these levels can be arranged into six series, which interact strongly with each other, the continua above the 4s²S_1/2 limit, and several interloper levels.