Precision measurements of the wavelengths of the Al XII 1snp1P1—1s2 1S0(n= 6–12) lines in the emission spectra of laser and X-pinch plasmas

The emission spectra of a high-temperature recombining laser plasma and of an X-pinch plasma were used in high-precision (± 0.03–0.05 pm) measurements of the wavelengths of the Al XII lines resulting from the 1snp1P1—1s2 1S0 (n = 6–12) transitions. The lines due to transitions from the 1s11p and 1s12p levels of the He-like Al XII ion were observed for the first time. The experimental results were compared with calculations carried out by several theoretical methods.