The first and second spectra of actinides are outstandingly rich. A list of 92000 lines of U I and U II was mentionned in (76.2). The published spectra of Pu I and Pu II totalize more than 30000 wavelengths (83.7). Publications with substantial line lists have been already recalled in the introductions to the energy levels Tables.

Emission lines of actinides have been compiled in a number of Tables. Only thorium and uranium (I and II spectra) were added to 68 other elements in Tables of Spectral Line Intensities by W.F. Metters, C.H. Corliss and B.F. Scribner, N.B.S., (U.S.A.), Monograph 145, parts I and II, (1975). The Tables of Spectral Lines by A.N. Zaidel, V.K. Prokofiev, S.M. Raiskü, V.A. Slownyi and E.Y. Schreider (I.F.I./Plenum, New York (1970)) include lines of multicharged ions. The compilation of "M.I.T. Wavelength Tables" by G.H. Harrisson (M.I.T. Press, Cambridge, MA, U.S.A., 1969) gave lines of Ac, Ra, Th and U.

In a more recent work by J. Reader, C.H. Corliss, W. Wiese and G.A. Martin, "Wavelength and Transition Probabilities for Atoms and Atomic Ions", N.S.R.D.S., N.B.S.- 68 (1980), selected strong lines were reported for all spectra described in the present work, except U III, IV, V, VI, Es I and Es II. The aim of the next section is to update and to complete this last compilation, the selected lines being generally the same. The wavelengths have been corrected eventually, the classifications have been added and the intensities have been revised in a few cases in agreement with recent data. The Atlases of thorium (83.9) and uranium (80.6) spectra recorded by Fourier Transform Spectrometry deserve a special mention. Several classifications in Pa, U, Cm, Bk, Cf and Es spectra are published below for the first time.