The shift and broadening of the resonance lines of Ca,Sr and Ba in hot,dense argon and helium

The shift and half-width of the resonance singlet lines of Ca, Sr and Ba in emission were measured under various relative densities between 20 and 70 for Ar (at 2500 K) and between 35 and 121 for He (at 2450 K) by means of a ballistic compressor. The shift due to Ar is always red and increased with increasing relative density. The shift due to He is slightly toward red at densities below 50 and then gradually turns to the violet as the relative density is further increased. The foreign gas shift and broadening is nearly the same for the resonance lines of all these different alkaline-earth atoms but is different for different foreign gases, as in the case of alkali metals. Comparison with previous observations of Ca at 910 K shows that the increase of temperature will cause a decrease in red shifts and half-widths.