Luminescence of the B ¹σ ⁺-X ¹σ ⁺ band system of MgO during plasma electrolytic oxidation of magnesium alloy

Abstract

A broad luminescence peak with clearly pronounced structure, extending from roughly 19,950cm -1 to 20,400cm -1 is obtained during plasma electrolytic oxidation of magnesium alloy (96% Mg, 3% Al, 1% Zn). It is assigned to the v'-v″=0 band sequence of the B 1σ +-X 1σ + emission transition of MgO. The measured intensity distribution is combined with quantum-chemical calculations in order to estimate the population of vibrational levels of the upper electronic state, and consequently to determine the plasma temperature. The composition of a plasma containing magnesium, oxygen, and hydrogen under assumption of local thermodynamic equilibrium is calculated in the temperature range up to 12,000K and for pressure of 10 5, 10 6, 10 7, and 10 8Pa, in order to explain the appearance of the observed spectral features. © 2011 Elsevier B.V.