The lifetime of the bound excited level in Ni$^-$

TL;DR

This paper reports a precise measurement of the intrinsic lifetime of an excited bound state in Ni$^-$ ions, using cryogenic ion storage rings, providing valuable data for understanding negative ion states.

Contribution

The study provides the first direct measurement of the intrinsic lifetime of the upper level in Ni$^-$, utilizing cryogenic storage ring techniques at DESIREE.

Findings

Intrinsic lifetime of Ni$^-$ upper level is 15.1 ± 0.4 seconds.

Ion storage lifetime at 13 K is approximately five minutes.

Cryogenic storage rings enable precise lifetime measurements of negative ions.

Abstract

The intrinsic lifetime of the upper level in the bound-bound 3d$^9$4s$^2$ $^2$D$_{3/2}$ $\rightarrow$ 3d$^9$4s$^2$ $^2$D$_{5/2}$ radiative transition in Ni$^-$ was measured to be 15.1 $\pm$ 0.4 s. The experiment was performed at cryogenic temperatures in one of the ion-beam storage rings of the DESIREE (Double ElectroStatic Ion Ring Experiment) facility at Stockholm University. The storage lifetime of the Ni$^-$ ion-beam was measured to be close to five minutes at a ring temperature of 13 K.