Identification of New Transitions in Fifth Spectrum of Cerium

The spectrum of four-times ionized Cerium has been observed with 3-m normal incident vacuum spectrograph in the 300-2000 angstrom wavelength region with triggered spark source. The Ab-initio pseudo relativistic CI calculations carried out for $5p^{6}$, $5p^{5}(4f+6p)$ and $5p^{5}(5d+6s+6d)$ configurations for even and odd system respectively, with the inclusion of interacting configurations using Cowan’s code. We have re-investigated previously determined levels of the $5p^{6}$, $5p^{5}4f$, $5p^{5}5d$, $5p^{5}6s$, $5p^{5}6p$ and $5p^{5}6d$ configuration. In the present analysis, we have identified 40 transitions, which are used to establish new energy levels belonging to $5p^{5}(5f+7s+8s)$ configuration.