Reaction of fluorine atoms with alkyl iodides: a possible observation of the Walden inversion in the gas phase

Evidence is presented to show that The Walden Inversion does take place in these gaseous reactions. CO/sub 2/ laser radiation of a mixture of SF/sub 6/ and alkyl iodides at equal pressures dissociated the SF/sup 6/ to F and SF/sup 5/. One ..mu..s later, the alkyl iodides were dissociated by a pulse from a dye laser. The experiment was repeated at 5 Hz. The resulting fluorescence intensities at 304.7 nm and 306.7 nm for I/sup */ atoms and excited I atoms are shown for methyl, ethyl, isopropyl, and tert-butyl iodide. From the relative intensities produced, conclusions can be drawn that a tertiary iodide does not produce any iodine atoms, while a primary iodide produces many more. Tests were performed to show that the iodine atoms were not photodissociated from the alkyl iodide cy the CO/sub 2/ laser or by 2-photon dissociation by the dye laser of the radical products of competing reactions. In the absence of SF/sub 6/, CO/sub 2/ laser pulses did not produce additional I atoms. 1 figure.