The role of repulsive forces in the shape of collision-broadened spectral lines and in the output of gas lasers

The shape of a collision-broadened spectral line taking into account an interatomic potential that includes both repulsive and attractive forces is obtained, in the impact approximation, using Anderson's formulation. Results for the lineshape, shift, broadening, and asymmetry are given for a general potential of the inverse power law form and for the Lennard-Jones potential. It is shown that inclusion of repulsive forces leads to results that exhibit experimentally observed behavior of the shift and asymmetry of a collision-broadened line in a range of conditions. Some comparison of experimental results and theoretical estimates for the 0.63-μ line of
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Ne in a
³
He-
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Ne discharge and in a
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Ne discharge at laser-operating conditions are given.