ISOTOPE SHIFT STUDIES IN THE UV SPECTRUM OF SINGLY IONIZED GADOLINIUM

Isotope shift Delta sigma(Gd-156-Gd-160) are reported for 33 spectral lines of singly ionised gadolinium (Gd II) in the 3315-3930 Angstrom r egion, making use of a photoelectric recording Fabry-Perot spectromete r and highly enriched isotopic samples of Gd-156 and Gd-160 Isotope sh ift values for these lines have not been reported earlier. Using this data, term isotope shift Delta T(Gd-156-Gd-160) have been evaluated fo r the even and odd parity energy levels involved in these transitions. We report here Delta T values of only 10 odd parity energy levels lyi ng above 35 000 cm(-1), which have been evaluated for the first time. Configuration assignments of six of these levels to 4f(8)6p have been confirmed and probable configurations suggested for four unassigned le vels. (C) 1998 Elsevier Science B.V.