Mass Spectrometric Analyses of the Ions Resulting from the Nuclear Decay of CH3I130 and C2H5I131. Study of Xenon—Hydrocarbon Ions. II

Ions resulting from the nuclear decay of CH3I130 and C2H5I131 have been measured with a specially designed mass spectrometer. From these two studies the percent abundances for the parent ions, [CH3Xe130]+ and [C2H5Xe131]+, are found to be, respectively, 34% and 1.4%. Besides CH3+ and C2H5+, formed directly from the severance of the C–Xe bond of the parent ions, a large variety of fragment ions are also observed. The results are compared with those for a similar study by us on CH3I131, (previously published in this Journal). From these comparisons the following conclusions are reached: (1) the ethyl—xenon ion undergoes decomposition much more readily than the methyl—xenon ion, and (2) the greater recoil energy that is present in the decay of I130 leads primarily to the severance of the organic—xenon bond, with the formation of CH3+. Besides recoil energy, there are also two other sources of excitation: (1) Coulombic shaking, as the result of the sudden change in nuclear charge following beta decay, is used to explain the appearance of the lower-charged Xe ions and most of the fragment hydrocarbon ions. (2) Multiple Auger processes following internal conversion are given as the cause for the more highly charged Xe ions, and their abundance is correlated with the amount of internal conversion present in I130 and I131.