Isotope shift studies in the first spectrum of dysprosium: confirmation ofassignments to 4f(10) 5d6p and new assignments to 4f(9)5d6s6p configuration

Isotope shifts Delta sigma (Dy-160-Dy-164) are reported for 221 spectral li nes of the neutral dysprosium atom (Dy I) in the region 470-565 nm using a photoelectric recording Fabry-Perot spectrometer and highly enriched isotop ic samples of Dy-160 and Dy-164 excited in liquid-nitrogen-cooled hollow-ca thode lamps. Isotope shift data for 173 of these lines are being reported f or the first time. Using the isotope shift data. term isotope shifts Delta T (Dy-160-Dy-164) have been evaluated for 99 even- and 68 odd-parity energy levels of Dy I. New Delta T values have been obtained for 24 odd and 36 ev en levels. These new Delta T values have enabled us to check some of the ex isting tentative assignments and also to suggest configuration assignments to a few unassigned energy levels. The earlier tentative assignments of 4f( 10)5d6p configuration to many high odd levels lying above 35000 cm(-1) have been presently confirmed. We could assign the 4f(9)5d6s6p configuration to 24 unassigned even levels.