Experimental Stark widths of Mo I and Mo II spectral lines in visible region

Abstract

In the last decade, molybdenum became a very important element for understanding the process of nucleosynthesis. An essential requirement for stellar spectral analysis is the availability of high-quality atomic data, including Stark broadening parameters. In this work we investigate Stark broadening of molybdenum spectral lines from the wavelength range 370 nm–510 nm. This is the first presentation of Stark widths for 18 Mo I and 18 Mo II spectral lines measured at an electron density of ≈ 1.5 × 1023 m−3 and electron temperature of ≈ 13000 K. Laser induced plasma with well isolated molybdenum spectral lines is employed as a radiation source. Spectra are recorded side-on; the line profiles are obtained via inverse Abel transform. Electron temperature is estimated using the Saha–Boltzmann method. To estimate electron density we applied two techniques. The first is based on the Saha–Boltzmann method for selected Mo I and Mo II spectral lines. In the second approach we rely on the measured width of the well-researched He I 388.86 nm line, as well as on the peak separation of the He I 447.15 nm line. Stark widths normalized to 1 × 1023 m−3 electron density are also given. The possible influence of isotope shift and hyperfine structure on spectral line profiles is discussed in detail. Stark shifts of investigated Mo I and Mo II spectral lines, if they exist, are below the detection limit of the experimental setup.