Observation of Electric Octupole Emission Lines Strongly Enhanced by an Anomalous Behavior of Cascading Contribution

Hiroyuki A. Sakaue, Daiji Kato, Izumi Murakami +2

We present extreme ultraviolet spectra of Ag-like W${}^{27+}$ observed with an electron beam ion trap. In the spectra, the $4f_{7/2,5/2}$ -- $5s$ transitions are identified as the f…