Determination of Ar metastable atom densities in Ar and Ar/H2 inductively coupled low-temperature plasmas

Ar metastable atoms are important energy carriers and surface interacting species in low-temperature plasmas that are difficult to quantify. Ar metastable atom densities (N_Ar,m) in inductively coupled Ar and Ar/H₂ plasmas were obtained using a model combining electrical probe measurements of electron density (N_e) and temperature (T_e), with analysis of spectrally resolved Ar plasma optical emission based on 3p → 1s optical emission ratios of the 419.8 nm line to the 420.1 nm line. We present the variation of N_Ar,m as the Ar pressure and the addition of H₂ to Ar are changed comparatively to recent adsorption spectroscopy measurements.