Hyperfine induced intensity redistribution in In \hbox{\sc II}

Abstract

We present a theoretical investigation of the hyperfine structure of the 5s5d 3 D 2 − 5s4f 3 F o 2,3 transitions in In ii. Earlier work has failed in determining hyperfine constants for the upper levels of these transitions. We show that this is due to strong off-diagonal hyperfine interaction, which not only changes the position of the individual hyperfine lines, but also introduces large intensity redistributions among the different hyperfine levels. We present hyperfine dependent gf-values and show that off-diagonal hyperfine interaction reduces some of the gf-values by two orders of magnitude, while others are increased by up to more than a factor of 6. We also discuss the influence on the hyperfine structure of an accurate representation of the level-splitting of the 5s4f configuration. We show that the hyperfine interaction in 3 F o 3 and 1 F o 3 is very hard to determine accurately even in a large scale calculation and we derive a semi-empirical method for adjusting our results using an experimentally known, diagonal hyperfine constant for 5s4f 1 F o 3. The resulting theoretical synthetic spectra reproduces the experimental to high accuracy and facilitate identification of all observed lines.

A NOVEL METHOD TO DETERMINE MAGNETIC FIELDS IN LOW-DENSITY PLASMA FACILITATED THROUGH ACCIDENTAL DEGENERACY OF QUANTUM STATES IN Fe9+

“…The procedure relies on radiation in the soft x-ray region of the spectrum, implying a space based method. This magnetic-field induced radiation originates from atomic transitions where the lifetime of the upper energy level is sensitive to the local, external magnetic field (Beiersdorfer et al 2003, Grumer et al 2014, Li et al 2014). We will show that there is a unique case where even relatively small external magnetic fields can have a striking effect on the ion, leading to resonant magnetic-field induced light, due to what is called accidental degeneracy of quantum states.…”

“…The origin of the new lines in the spectra of ions is the breaking of the atomic symmetry by the external field, which will mix atomic states with the same magnetic quantum number and parity. This will in turn introduce new decay channels from excited states (Andrew et al 1967, Wood et al 1968), which we will label magnetic-field induced transitions (MITs) (Grumer et al 2014). These transitions have attracted attention recently, when accurate and systematic methods to calculate their rates have been developed (Grumer et al 2013.…”

The anomalous hyperfine structure of Al II

“…For example, Jomaron et al [2] showed that the abundance of Mn in chemical peculiar HgMn stars can be overestimated by two or three orders of magnitude if the hyperfine structure is not taken into consideration. They also showed that if the hyperfine structure is only included in a crude model the abundance can still be overestimated by a factor of 4. In two earlier papers we have developed theoretical models and investigated the intensity redistribution in parts of the Ga II [3] and In II spectra [4], reproducing experimental spectra that had earlier not been fully understood by Karlsson and Litzén [5,6]. Both Ga II and In II are essentially two-electron systems and their spectra should therefore be fairly easy to understand.…”

HYPERFINE-DEPENDENT gf -VALUES OF Mn I LINES IN THE 1.49-1.80 μm H BAND

“…In this work, we have used the latter approach. We will not describe the method in detail in this paper, but we refer to three earlier papers that were based on similar approaches, Andersson et al (2006), Grumer et al (2010), andAndersson et al (2012).…”