Li I spectra in the 4.65-8.33 micron range: high-L states and oscillator strengths
Li I spectra in the 4.65-8.33 micron range: high-L states and oscillator strengths
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DOI：
10.1051/0004-6361/201219852
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发表时间：
2012-09-01
影响因子：
6.5
通讯作者：
Zanozina, E. M.
中科院分区：
文献类型：
--
作者：
Civis, S.;Ferus, M.;Zanozina, E. M.
上下文近年来，由于几个地面和空间设施，红外天文学能力迅速发展。为了有效地利用这些功能，需要大量的原子数据（如线波数，激发能级能量值和振子强度）。这些数据是不完整的，特别是锂的丰度对几个天体物理问题很重要。没有实验室测量的光谱的Li I已经报告的波长longward的6.6微米。我们的目标是在4.65-8.33微米范围内发现新的Li I线，这是由于高轨道动量（l >= 4）的状态之间的跃迁，并确定这些状态的激发能。利用时间分辨傅里叶变换红外光谱研究了真空中激光烧蚀LiF靶产生的等离子体的Li I谱线。通过考虑使用量子亏损理论（QDT）计算的振子强度（f值）来进行线的分类。通过与现有的实验和理论结果进行比较，检查QDT对这些计算的适当性。我们报道了在900-2200 cm（-1）范围内的四条新的Li I谱线，这使我们能够提取Li I的6 g，6 h和7 h态的激发能，这是以前没有测量过的。我们还提供了一个大的列表QDT计算的f值为Li I在1-20微米的范围内。
Context. Infrared (IR) astronomy capacities have rapidly developed in recent years thanks to several ground-and space-based facilities. To take advantage of these capabilities efficiently, a large amount of atomic data (such as line wavenumber, excited-level energy values, and oscillator strengths) are needed. These data are incomplete, in particular, for lithium whose abundances are important for several astrophysical problems.Aims. No laboratory-measured spectra of Li I have been reported for wavelengths longward of 6.6 microns. We aim to find new Li I lines in the 4.65-8.33 microns range due to transitions between states with high orbital momentum (l >= 4) and to determine the excitation energies of these states.Methods. The Li I lines were studied using the time-resolved Fourier transform infrared spectroscopy of a plasma created by the laser ablation of a LiF target in a vacuum. The classification of the lines was performed by accounting for oscillator strengths (f-values) calculated using quantum defect theory (QDT). The adequacy of QDT for these calculations was checked by comparison with the available experimental and theoretical results.Results. We report four new Li I lines in the 900-2200 cm(-1) range that allow us to extract the excitation energies of the 6g, 6h, and 7h states of Li I, which have not been measured before. We also provide a large list of QDT-calculated f-values for Li I in the range of 1-20 microns.