The hyperfine structure of 129I2 and 127I 129I in the B3Π0u+-X1Σg+ band system

In a double saturation spectroscopy experiment, using the radiation from one single frequency cw laser, the spectra of I-129(2) and (II)-I-127-I-129 from one saturation setup were recorded simultaneously and with respect to the spectrum of I-127(2) from another setup while tuning the laser. The hyper. ne patterns of I-129(2) and (II)-I-127-I-129 were analysed to determine the nuclear electric quadrupole interaction and the nuclear spin-rotation interaction parameters. Models are presented describing the observations and giving reliable predictions for the hyper. ne parameters of all isotopomers.