Analysis of the Light Emission Originating from Dissociative Recombination Process in Argon Afterglows

The spectrum of emitted light of the afterglow in the range of 400 to 850 nm has been measured in the argon afterglow at 665 Pa. Every Ar*line observed has been attributed to transitions from 4p→4s, 4p′→4s, 4p′→4s′and 5p→4s. We have observed experimentally that transitions from 5p levels reveal quite different behavior from those from 4p and 4p′levels. The light intensity from the 5p→4s transitions decayed to a minimum value within 10 µ s after the termination of the discharge and thereafter increased quickly to a maximum in 23 to 28 µ s followed by a slow decay. The light from the 4p→4s, 4p′→4s and 4p′→4s′transitions exhibited a sharp decay in about 20 µ s, which was followed by a slow decay. We have analyzed the temporal decay of the emitted light and also attributed the rapid increase of the light intensity due to the increase of the coefficient of the dissociative recombination which may be caused by the rapid decay of electron temperature in the early afterglow.