Infrared transitions and oscillator strengths of Ca and Mg^⋆

¹ J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 18223 Prague 8, Czech Republic
e-mail: civis@jh-inst.cas.cz
² Voronezh State University, 394693 Voronezh, Russia
e-mail: chernov@niif.vsu.ru
³ State Research Center of Russian Federation Troitsk Institute of Innovation and Fusion Research, 142190 Troitsk, Moscow Region, Russia

Received: 7 January 2013
Accepted: 24 March 2013

Abstract

Aims. While solar spectra contain a lot of Ca I and Mg I infrared (IR) lines, no laboratory-measured spectra of these atoms have been reported for wavenumbers below 2000 cm^-1. This study reports Ca I spectra in the 1300–4500 cm^-1 range and Mg I spectra in the 1300–4500 cm^-1 range.

Methods. We performed a time-resolved Fourier transform infrared spectroscopy study of a plasma created by the laser ablation of MgF₂ and CaF₂ targets in a vacuum. The oscillator strengths (f-values) were calculated using quantum defect theory (QDT), which shows good agreement with the available experimental and theoretical results.

Results. We report several Ca I and Mg I IR lines that have not been measured previously in laboratory. The recorded spectra allow the excitation energies of some Ca I and Mg I states with high orbital momentum (l = 4,5) to be determined. We also provide a long list of QDT-calculated f-values for Ca I and Mg I in the range of 800–9000 cm^-1.