Transition probability ratios in the Mg I 3p-4s transition

Using the relative line intensity I ratios of the astrophysically important 518.360 nm, 517.268 nm and 516.732 nm neutral magnesium (Mg I) lines in the 3p 3Po 0,1,2 - 4s 3S1 transition we have obtained the ratios of corresponding transition probability values (Einstein's A values). They represent the first experimental data based on the analysis of the emission spectral lines. The linear, low-pressure, pulsed arc was used as a plasma source operated in the helium with magnesium atoms introduced as impurities from discharge electrodes, providing there is no self-absorption within the investigated range of Mg I spectrum. We have found excellent agreement with theoretical transition probability ratios tabulated by NIST (2003).