Critical compilation of wavelengths and energy levels of singly ionized beryllium (Be II)

Energy levels and wavelengths of the second spectrum of beryllium (Be II) were critically compiled. Energies of the levels involving excitation of the valence electron were re-optimized using the new data on transition wavelengths or calculated using precise semi-empirical formulas. Energies of the doubly-and triply-excited terms were taken from the recently published compilation [kramida, A. E., Physica Scripta 57. 66 (1998)] or obtained from recently published Auger electron spectra. Observed wavelengths and wavelengths calculated from the differences of the upper and lower levels are given together with their uncertainties.