CI-MBPT line strengths and atomic probabilities for some transitions of neutral iodine

Abstract

Iodine is a promising alternative to expensive xenon as a propellant for electric propulsion devices. Iodine optical spectroscopy is a valuable diagnostic tool for optimization of the iodine propellant. Recently, some measurements have been conducted with cells containing iodine plasma, and iodine atomic absorption at several wavelengths (911, 906, 206 and 1315 nm) was measured with a Ti:sapphire laser. Motivated by these experiments and future applications, we have calculated line strengths and atomic probabilities for the transitions between different types of 5s25p5, 5s25p46s, 5s25p46p and 5s25p45d states of atomic iodine, using configuration-interaction many-body perturbation theory. Since experimental transition data for atomic iodine are only available for a relatively small number of transitions, we also performed calculations for the bromine atom, to further validate our approach. We found good agreement between our theory and available experimental data for both elements in most cases. Therefore, we believe that our predicted line strengths and transition probabilities are quite reliable and will be useful for iodine spectroscopy.

Two-photon absorption laser induced fluorescence (TALIF) detection of atomic iodine in low-temperature plasmas and a revision of the energy levels of I I

“…A stronger coupling is also expected from the lower, 2 P 3/2 , level, when going to the next excited, ( 3 P 0 )6s 2 [0] 1/2 level (Lawrence 1967), yet the absolute intensity of the corresponding lines appeared experimentally as rather weak ones, and with similar intensities (Kiess and Corliss 1959). But, just going to the following excited levels, one already finds a coupling to the ( 3 P 1 )6s 2 [1] doublet stronger from the 2 P o 1/2 level than from the ground 2 P o 3/2 one (Kiess and Corliss 1959, Filin et al 2020, Kramida et al 2021. In the present state of our knowledge of the I I spectrum, there is thus no reason (apart from the factor of 1/2 given by the degeneracy ratio) to think that the two-photon excitation scheme shall be less efficient for 2 P o 1/2 than for 2 P o 3/2 detection.…”

“…We did not observe any signal, which may be due to a relatively high quenching rate of the 2 P o 1/2 level down to the ground 2 P o 3/2 level at the densities used or, inclusively, to the weakness of the TALIF transitions chosen for detection. The latter explanation could be supported by the relative weakness of the 206 nm line, when compared to the much more intense 183 and 178 nm ones (Kiess and Corliss 1959, Lawrence 1967, Filin et al 2020, Kramida et al 2021, which reveals larger electric dipole matrix elements to the first, ( 3 P 2 )6s 2 [2], term starting from the ground level than from the fine-structure excited 2 P o 1/2 . However, even though the ( 3 P 2 )6s 2 [2] term is the most favorably weighted, as the one closest to one-photon resonance, many more virtual intermediate states contribute to the series of dipole-products that makes the two-photon transition amplitude.…”

“…To guide the theoretical calculations concerning the operation of thrusters (Grondein et al 2016, Levko andRaja 2021), especially at low pressure, the literature lacks basic data describing the chemical reactions of various species, although there is a renewed interest in new calculations, such as electron impact collisions cross-sections on I and I 2 (Ambalampitiya et al 2021) or line strengths and atomic probabilities for some transitions of neutral iodine (Filin et al 2020). Electrical or optical diagnostics are also rare.…”

Atomic spectrometry update: review of advances in atomic spectrometry and related techniques

“…Several groups contributed to the body of work on fundamental constants; namely oscillator strengths of transitions from the 6d7p 3 F o 2 to the 7s6d 3 D 1 , 7s6d 3 D 2 , and 7s6d 1 D 2 states in 226 Ra; 73 transition probabilities and line strengths for transitions between different types of 5s 2 5p 5 , 5s 2 5p 4 6s, 5s 2 5p 4 6p and 5s 2 5p 4 5d states of atomic I; 74 and transition probabilities of Ag I lines at 827.35 and 768.77 nm. 75…”

“…Pons et al 167 set out a revised analytical scheme for Se using a 76 Se- 78 Se double spike. This was chosen over the 82 Se- 78 Se and 74 Se- 77 Se spikes as it was predicted to generate lower analytical uncertainties over a much larger range of spike-sample mixing. However, a disadvantage of 76 Se- 78 Se is that both masses are isobaric with Ar dimers, e.g.…”