Hyperfine structure study of atomic niobium with enhanced sensitivity of Fourier transform spectroscopy

Abstract

In an experimental setup with a high-resolution Fourier transform (FT) spectrometer and a hollow-cathode discharge, bandpass interference filters are used to enhance the sensitivity. This extension leads to an improvement of the signal-to-noise ratio in the spectrum of atomic niobium by a factor of up to 10 compared to FT spectra measured previously without filters (see Kröger et al 2010 Astron. Astrophys. 516 A70). Several additional spectral lines with low intensity have been observed. Additionally, in some intense lines, blends become visible due to the better signal-to-noise ratio. The hyperfine structure of 51 lines recorded in the wavelength range from 415 to 670 nm is analysed or re-analysed and magnetic dipole hyperfine structure constants A of 8 levels of even parity and 43 levels of odd parity are determined. Improvement of sensitivity of FT spectroscopy in the visible wavelength range enabled the determination of new hyperfine structure constants A for two energy levels of even parity, which fill the last gaps for energetically low-lying levels below 14 000 cm−1. Additionally, ten new A constants for energetically higher lying levels of odd parity as well as several improved A values have been obtained.

Hyperfine structure investigations of atomic niobium with optogalvanic and laser-induced fluorescence spectroscopy in the near-infrared wavelength range

“…We here continue our earlier systematic investigations of the spectrum of Nb I Kröger et al 2004Kröger et al , 2007Kröger et al , 2010Başar et al 2008;Er et al 2011). Our purpose is to supplement hyperfine structure (hfs) data for this element, in particular, to fill gaps for all energy levels of even parity with unknown hyperfine structure (hfs) constants.…”

“…t.w. : this work; (1) Fraenkel et al (1988); (2) Er et al (2011); (3) Bouzed et al (2003); (4) Başar et al (2008); (5) Kröger et al (2010). Notes.…”

“…Other high-resolution measurements have been made by Fraenkel et al (1988) using laser and radio-frequency spectroscopy, and by some of us (Başar et al 2008), using Doppler-reduced saturation absorption spectroscopy. Doppler-limited measurements of hfs constants have been made using Fourier transform spectroscopy (Kröger et al 2010;Er et al 2011) and Doppler-limited laser spectroscopic methods (Singh & Rao 1989;Singh et al 1992;Bouzed et al 2003;Kröger 2007). In addition to the experimental investigations, a theoretical analysis of hfs of atomic Nb has been performed by , , and Kröger et al (2007).…”

Radiative lifetimes of odd-parity levels in Nb I

“…Niobium has only one naturally abundant isotope, 93 Nb and it has the largest nuclear magnetic dipole moment among the stable nuclei. Thus the atomic levels of Nb have a broad hyperfine splitting [13,14]. As the frequency spread (1/Δτ $ 100 MHz) corresponding to the duration of the excitation pulse cannot cover the large hyperfine splitting, which is of the order of few hundreds of MHz, pairs of nondegenerate magnetic sublevels cannot be coherently excited [15].…”

Division B Commission 14 Working Group: Atomic Data

“…Al II (HFS): [26], Ar IX: [277], B II: [208], Br III: [140], Cl I: [300], Co II (forbidden): [256], Dy I: [292], Eu I (HFS,IS): [2,102,103,104], Fe VIII-IX: [230], Fe VIII-XVI: [37], Fe XI: [66], Fe XIII: [62], Fe XVI: [36], Fe XVII: [63], Fe XVIII: [54], Fe XVIII-XXV: [254], Gd I (IS,HFS): [145], I I: [124], K I: [51], K III: [22], La I: [106], Li I: [50], Mg VII-VIII: [177], Mn I (HFS): [25,165], Mn II : [46], N III: [112], Na I: [52], Nb I: [72,235], Nb I (HFS): [95], Nd II (HFS): [28], Ne IV : [170], Ni I: [288,291], O I: [204], O VI: [341], P II: [153], Pr I (HFS): [107,282,319], Pr II: [21], Pr II (HFS): [20], Ru I (IS,HFS): ...…”