read more
Home arrow Document
   
Subscriber Authentication Point
 
   
Issue A&A
Volume 467, Number 2, May IV 2007
Page(s) 753 - 760
Section Atomic, molecular, and nuclear data
DOI 10.1051/0004-6361:20077108



A&A 467, 753-760 (2007)
DOI: 10.1051/0004-6361:20077108

Accurate Ritz wavelengths of parity-forbidden [ $\ion{ii}$], [ $\ion{ii}$], and [ $\ion{ii}$] infrared lines of astrophysical interest

M. Aldenius and S. Johansson

Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden
    e-mail: [maria;sveneric.johansson]@astro.lu.se

(Received 16 January 2007 / Accepted 6 March 2007 )

Abstract
Context.With new astronomical infrared spectrographs the demands of accurate atomic data in the infrared have increased. In this region there is a large amount of parity-forbidden lines, which are of importance in diagnostics of low-density astrophysical plasmas.
Aims.We present improved, experimentally determined, energy levels for the lowest even LS terms of $\ion{ii}$, $\ion{ii}$ and $\ion{ii}$, along with accurate Ritz wavelengths for parity-forbidden transitions between and within these terms.
Methods.Spectra of $\ion{ii}$, $\ion{ii}$ and $\ion{ii}$ have been produced in a hollow cathode discharge lamp and acquired using high-resolution Fourier Transform (FT) spectrometry. The energy levels have been determined by using observed allowed ultraviolet transitions connecting the even terms with upper odd terms. Ritz wavelengths of parity-forbidden lines have then been determined.
Results.Energy levels of the four lowest $\ion{ii}$ terms (a6D, a4F, a4D and a4P) have been determined, resulting in 97 different parity-forbidden transitions with wavelengths between 0.74 and 87 $\mu$m. For $\ion{ii}$ the energy levels of the two lowest terms (a4F and b4F) have been determined, resulting in 24 different parity-forbidden transitions with wavelengths between 8.9 and 130 $\mu$m. Also for $\ion{ii}$ the energy levels of the two lowest terms (a6S and a6D) have been determined, in this case resulting in 12 different parity-forbidden transitions with wavelengths between 0.80 and 140 $\mu$m.


Key words: atomic data -- line: profiles -- methods: laboratory -- techniques: spectroscopic -- infrared: general



© ESO 2007


What is OpenURL?