Etude Expérimentale et Théorique de l'Iode Atomique. Observation du Spectre d'Arc Infrarouge, Classification et Structure Hyperfine

The infrared spectrum of127I, nuclear spinI= 5/2, has been observed between 3 000 and 11 500 cm-1at high resolution by means of the Fourier transform spectrometry method. We have observed 440 structures. Precise measurements of the centre of gravity of these structures give energy levels with an error less than 0.005 cm-1. We have analysed 130 hyperfine structures, giving the magnetic dipole and the electric quadrupole hyperfine structure constants for 37 even levels and 42 odd levels. The intermediate coupling has been studied for the even configurations 5s25p4(6s+ 7s+ 5d+ 6d) + 5s5p6simultaneously, and for the odd configurations 5s25p4(6p+ 7p) and 5s25p44f. Using the wavefunctions obtained, hyperfine structure parametric studies have been performed, giving the H.F.S. monoelectronic constantsa(nl) andb(nl). An a priori study of hyperfine structure, using the relativistic central potential method makes clear the important contribution of relativistic effects and leads one to think that distant configuration interaction effects are negligible in the excited configurations which have been studied.