Optical emission spectroscopy of diaphragm discharge in water solutions

This work is focused on optical emission spectroscopy observations of DC non-pulsed diaphragm discharge in various water solutions of sodium and potassium salts. The emission intensity dependencies of hydrogen, oxygen, and alkaline metal lines on the salt kind are studied and compared also with respect to the initial solution conductivity. The hydrogen and oxygen intensities increase more or less linearly with the increasing solution conductivity. The sodium intensity behaves identically, but the potassium intensity decreases with the conductivity increase. The hydrogen intensity is higher in the case of salts containing potassium. The dependence of the H alpha line intensity on the salt kind is lower than if a sodium salt is used. The oxygen emission is more or less independent on the used salt. In addition, the rotational temperature from the OH radical spectrum is calculated for the investigated electrolytes and it is in the range from 500 to 900 K, according to the initial solution conductivity. The dependence of the rotational temperature on the salt kind is not clear so far.