Analysis of the He(3 3S)-He(2 3P) line profile obtained in dense helium plasma

The emission spectrum produced at 300 K in dense plasmas of helium excited by a corona discharge shows an asymmetric atomic line at 706 nm that may be associated with quasi-molecular states of He2. We present here the first calculations of He-He collisional profiles of this line done in a unified line shape semi-classical theory using ab initio molecular potentials. The excellent agreement between experimental and theoretical determinations of the near wing of the line profiles establishes the accuracy of the interaction potentials. The strong pressure dependence of the collision profiles can then be used as a diagnostic of the physical parameters of the source. (authors)