Active Control of the Relative Population of ³P₀ Fine-State in the Glow Discharge of a Supersonic Ar Beam

An active control for changing the relative population of the ³P₀ fine-state of Ar* in a supersonic beam was investigated in a glow discharge by adding a small amount of foreign gases to pure Ar gas. The Ar* mean velocity was determined to be constant at major positions of the time profile, except for a rise and the decay of the beam for all gas mixtures, and also pure Ar. The relative population of ³P₀ decreased with the discharge potential for the addition of ethylene, cyclohexane, and benzene. However, the addition of N₂ and CH₄ and pure Ar, did not show such a ³P₀ decrease. These dissimilar behaviors of the foreign mixed gases could be interpreted based on a difference in the ionization potential of the molecules. A useful application of this population control is discussed.