Resonant ionization spectroscopy of autoionizing Rydberg states in cobalt and redetermination of its ionization potential

Abstract

Multi-step resonance ionization spectroscopy of cobalt has been performed using a hot-cavity laser ion source and three Ti:Sapphire lasers. The photoionization spectra revealed members of five new autoionizing Rydberg series that originate from three different lower levels of 3d 7 4s5s h 4 F 9/2 , 3d 7 4s4d f 4 G 11/2 , and 3d 7 4s4d f 4 H 13/2 and converge to the first four excited states of singly ionized Co. The analyses of the Rydberg series yield 63 564.689±0.036 cm −1 as the first ionization potential of Co, which is an order of magnitude more accurate than the previous estimation. Using a three-step resonance ionization scheme that employs an autoinizing Rydberg state in the last transition, we obtained an overall ionization efficiency of about 18% for Co.

Relativistic R-matrix photoionization cross section calculations of Ne-like Co XVIII with resonance parameters

“…Cobalt is produced in α-rich freeze-out in SNe [6]. A recent detection of cobalt in a damped lyman alpha system and the revelation of 56 Co in a type Ia SNe suggests that it could be an important element in galactic chemical evolution studies [7,8]. Transition lines of cobalt are useful for astronomical probes especially in investigating the observational data of SNe where these emissions can be helpful in assessing the nucleosynthesis and decay processes related with the SNe explosion [9].…”