✍ Scribed by M Sassi; C Deutsch; G Coulaud
No coin nor oath required. For personal study only.
The inclusion of a frequencydependent collision operator in the line shape expression is investigated quantitatively for the 4471 A overlapping He1 line. We compare at several electron densities frequency-independent (markovian) profiles with frequencydependent (nonmarkovian) profiles taking into account incomplete electron-atom collisions. No significant discrepancies appear in the domain of validity of the impact approximations (1 dw 1 < up,), whereas for the far wings important differences may be found. At the extrema (two peaks, one dip) the nonmarkovian intensities prove to be the higher ones. For a modest electron density, the inclusion of ion dynamic shielding introduces more modifications then nonmarkovian effects. In the blue wing, the frequency-dependent profile lies below the frequency-independant profile in accord with the hydrogenic behavior for that part of the line shape in the presence of a large perturber density.
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