JET EMISSION-SPECTRA OF CDI AND HGI AND NEAR-DISSOCIATION THEORY ANALYSES FOR CDI AND ZNI

Emissions from CdI and HgI produced in a corona-excited supersonic jet discharge were photographed in high resolution. A study of the vibrationally and isotopically resolved spectra for the CdI ultraviolet D2-PI-3/2-X2-SIGMA+ transition near 338.4 nm and visible B2-SIGMA+-X2-SIGMA+ transition near 646.5 nm has yielded vibrational constants for the X, B, and D electronic states and estimates of their dissociation energies. Use of near-dissociation expansion analyses has yielded much mom reliable extrapolation properties for this system, and for the analogous states of ZnI, than use of conventional techniques. The analysis of the HgI B-X spectrum near 420 nm was found to be in excellent agreement with previous studies. The trends in the X- and B-state constants for the MI series (M = Zn, Cd, Hg) including dissociation energies derived from near-dissociation theory are rationalized in terms of the mixed ionic-covalent bonding expected for group IIB metal halide radicals.