N-I and N-II Spectra and Mean Lifetimes Measureed by a new Technique of Beam-Foil Spectroscopy with a Charge-Couple- Device

A new method for measuring spectra and decay curves in beam-foil spectroscopy is described and some initial results presented. A charge-coupled device (CCD) is used to record simultaneously all points on a decay curve. A telecentric optical system ensures that the spectral resolvance is close to the irreducible limit (set by angular divergence of the atomic beam) and that no systematic distortion of the decay curve can occur. Values of mean lifetimes are reported in N II for 11 levels derived from decay curves for 15 lines in the wavelength range 500-700 mum. In addition decay curves have been measured for 5 blends, each of lines within the same N II multiplet; also some measurements for N I lines in the wavelength range 700-900 mum are reported.