Self broadening and f -values in the spectrum of neon

Abstract

Profiles of lines in the NeI spectrum arising from transitions between the configurations 2 p 5 3 s and 2 p 5 3 p were measured by means of a direct-recording Fabry–Perot interferometer. The d. c. discharge was cooled with liquid nitrogen or ice and currents were typically 0·5 mA. Full analysis of the profiles determines the pressure broadening as a Lorentzian component. For lines with the lower level 2 s 2 (Paschen notation) the broadening can be ascribed to the resonance interaction alone and the f -value of 0·16 8 is obtained for the resonance transition 736 Å. From coupling parameters the f -value of the transition 744 Å is estimated as 0·01 2 which is consistent with the broadening observed for the lines with the lower level 2 s 4 . The nature of the higher order interactions is discussed with reference to the observed temperature dependence and pressure shifts. Extrapolation of the Lorentzian width to zero density and the subtraction of a carefully determined instrumental contribution gives a value in excess of the radiation width for the level 2 s 2 , a result similar to that reported for the level 2 1 P 1 in helium. The explanation of this anomaly as an enhancement effect is discussed.