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

Abstract

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 first observation of spontaneous electric octupole emission. Our theoretical investigation shows that the emission line intensity is strongly and specifically enhanced at the atomic number 74 by an anomalous behavior of cascading contribution to $5s$ via $5p\leftarrow 5d$.

References in corpus (8)

• Spectroscopy of diagnostically-important magnetic-dipole lines in highly-charged 3d${}^n$ ions of tungsten
• Solar coronal lines in the visible and infrared. A rough guide
• Analysis of the fine structure of Sn${}^{11+...14+}$ ions by optical spectroscopy in an electron beam ion trap
• Third-order relativistic many-body calculations of energies and lifetimes of levels along the silver isoelectronic sequence
• Density dependence of the forbidden lines in Ni-like tungsten
• Visible emission spectroscopy of highly charged tungsten ions in LHD: II. Evaluation of tungsten ion temperature
• Visible transitions in Ag-like and Cd-like lanthanide ions
• Theoretical investigation of spectroscopic properties of W${}^{26+}$ in EBIT plasma

Cited by in corpus (1)

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