HIGH-DENSITY SELF-BROADENING OF NEON 3S-3P ATOMIC SPECTRAL-LINES STUDIED BY LASER-ABSORPTION SPECTROSCOPY

The self-broadening of four neon atomic lines (1s(5)-2p(2), 1s(4)-2p(2 ), 1s(3)-2p(2) and 1s(2)-2p(1)) belonging to the 3s-3p transition grou p has been measured for the first time at high pressures (1-6 bar) and a low gas temperature (330 K), through a laser absorption spectroscop y technique. Pulsed x-ray photoswitched discharges have been used for the experiment. In our experimental conditions, the line profiles are found to be Lorentzian in shape, with a symmetric core with respect to a shifted line centre. Linear variations with the pressure are report ed for the broadenings and the shifts. Broadening and shift constants relevant for the density range studied are deduced. These constants ar e in overall agreement with the low density results previously publish ed, but new features are reported: extrapolation to zero pressure of t he shifts measured above 1 bar does not give a zero value for the 1s(5 )-2p(2) and 1s(4)-2p(2) lines, and a blue shift is measured for the 1s (2)-2p(1) line. Assuming approximate interaction potentials, the impac t theory gives broadening constants close to the measured ones. Nevert heless, the interpretation of the shift behaviours requires the use of unified theories including many-body collision effects.