An Experimental Study of 3s²3pkand 3s3pk+1in the CI I, S I, P I, Si I, and AI I Isoelectronic Sequences

New measurements and identifications of the transitions 3 s 2 3 p k -3 s 3 p k +1 have been made in the spectra of S IV, K IV-VII, Ca V-VIII, Sc VI-IX, Ti VII-X, V VII-XI, Cr VIII-XI, Mn IX-XI, and Fe X, XI. The energy parameters of the ground configurations have been determined and expressed as functions of Z by semi-empirical formulae in the S I, P I, Si I, and Al I isoelectronic sequences. Predicted wavelengths for some 150 forbidden lines of astrophysical interest are tabulated.