The vacuum ultraviolet absorption spectrum of diatomic calcium

Calcium granules (99.5%) have been heated to 615°C in a tantalum furnace and the absorption spectrum has been observed on the SA 61 beam line of SUPERACO (Orsay) using a 3-metre Balzers monochromator down to the LiF cut-off (1015 A). An intense Rydberg series has been observed between 1900 and 1500 A. This series extends from n = 5 to n = 12 and gives the ionization potential at 63068 cm - 1 (1585.6 A) or 7.819eV and the quantum defect δ = 1.73.