Abstract
High resolution (+or-0.003 AA) absorption spectra of CH3I have been recorded by using synchrotron radiation in the wavelength range from 1800 to 1130 AA. The spectra show high members of the ns, np and nd series converging on the 2E3/2 and 2E1/2 levels of CH3I+ as well as the nd series terminating on a nu '=1 vibrational level of 2E1/2. All the series have been considerably extended up to n values superior to the corresponding series in atomic Xe I and further detail added to previously known structures. A preliminary interpretation is presented and accurate values for the ionisation potentials are derived.