Population measurement of the 3p54s configuration levels in an argon microwave plasma at atmospheric pressure

Metastable atoms, due to their intrinsic properties, are very useful to characterize plasma and to control the scientific and technological applications carried out with it. This paper describes the implementation of a method to determine the densities of the argon 3p(5)4s metastable and resonant levels in a microwave plasma at atmospheric pressure. Because the method is based on the self-absorption of the radiation emitted by the plasma, no external radiation source is needed. Using this method, the populations of the four levels of the 3p(5)4s argon configuration were found to be in the range 10(10)-10(12) cm(-3), in agreement with the values found in the literature.