The spectrum of singly ionized yttrium, Y II
Hollow-cathode spectra of yttrium have been registered in the wavelength region 1000-48 800 Å. Resonant charge transfer reactions in the light source favour the excitation of Y II, where 174 new levels have been established by means of 1284 newly classified lines. Altogether we report 1521 lines between 235 levels in Y II. The ground complex (4d + 5s)2 is now completely known and a number of Rydbe