The Transitions 4p-5s in Y VI, Zr VII, Nb VIII and Mo IX

With the help of the spectra recorded in the Physics Department of Lund University, Y VI, Zr VII, Nb VIII and Mo IX are freshly analysed. The five 4s24p4ground levels and the ten 4s24p35slevels of previous analyses are confirmed in the first three spectra, except for revising in Y VI the 4p41S0and 4p35s(4S3/2)2levels and interchanging 5s(2D3/2)1with 5s(2D3/2)2. All level values are improved due to our new measurements. A new analysis of Mo IX establishing all the 4p4and 4p35slevels is being reported.