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.