Our contribution presents the latest results of our study of the DC glow discharge in oxygen and in oxygen-nitrogen mixture. The discharge was studied at medium pressures (0.65-17.5 kPa), where both the so-called T- and H-forms of the positive column can be present.
The spectrometer Jobin-Yvon TriAx 550 was calibrated using tungsten lamp. Absolute values of excited atomic oxygen mean concentration were calculated for the O I 5P triplet (777 nm).
The concentration was higher at higher pressures and discharge currents. It was also significantly higher in an H-form than in a T-form.