Stark Broadening of UV Nickel Lines

Extract

Widths of Stark broadened Ni I Lines in the spectral range of 3000 Å–4000 Å have been measured using a gas driven shock tube as a spectroscopic source. Electron densities were determined using measured pressure and temperature data. Within the density range 6 × 10¹⁶ cm^-3 to 12 × 10¹⁶ cm^-3 the observed widths were linear functions of the electron density. There was no apparent correlation of observed widths with neutral density. Van der Walls broadening was presumed to be negligible because we observed narrow lines which should have had the same Van der Walls widths as computed with a classical theory as some of the wide lines we observed. In this way we were able to attribute almost all of the observed broadening to the Stark effect. The experimental results were compared with results of calculations of Stark broadening parameters using the program developed by Cooper and Oertel. The measured widths were about a factor three larger than the theoretical predictions. A part of this discrepancy is probably due to the fact that only LS allowed interactions were considered in the broadening calculations and possible incomplete classifications.