Experimental transition probabilities in the Ar III and Ar IV UV spectra

We present transition probabilities (Einstein's A values) for 38 Ar III (doubly ionized argon) and 14 Ar IV (triply ionized argon) spectral lines from the wavelength interval 240-308 nm. Considered spectral lines are recorded in laboratory pulsed discharge. The relative line intensity ratio procedure has been applied in evaluation of transition probabilities. As a reference for transition probability evaluation we have chosen A value of 241.884 nm spectral line in Ar III spectrum and A value of 280.947 nm in Ar IV spectrum, both obtained theoretically. Careful analysis of experimental and existing theoretical data is conducted in order to deduce uncertainties. Presented Ar III and Ar IV A values are for the first time obtained relying on experimental data.

► We measured transition probabilities of Ar III (38 transitions) and Ar IV (14 transitions). ► Relative line intensity ratio method is applied. ► Argon pulsed discharge is employed as a light source. ► Error analysis based on the Boltzmann-plot is presented. ► The agreement with recently calculated Ar III values is found.