Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths of Some Levels in Er i and Er ii

Radiative lifetimes for 104 levels of Erbium (Er) I in the energy range between 31,926.003 and 44,525.705 cm(-1) and 51 levels of Er II from 31,381.779 to 47,840.962 cm(-1) were measured by a time-resolved laser-induced fluorescence method. Branching fraction (BF) determinations for 356 lines from 47 out of 104 Er I levels and 122 lines related to 19 out of 51 Er II levels were completed based on the emission spectra of hollow cathode lamps recorded using the 1.0 m Fourier transform spectrometer and are available from the digital library of National Solar Observatory on Kitt Peak, USA (http://diglib.nso.edu/). By combining these BFs and the lifetime results measured in this work, absolute transition probabilities and oscillator strengths were determined for 352 lines of Er I and 92 lines of Er II for the first time, increasing the total number of lines with experimental transition probabilities to over 910 for Er I and over 540 for Er II.