Measurement of the Relative Abundances and Recoil-Energy Spectra of Fragment Ions Produced as the Initial Consequences of X-Ray Interaction with CH3I, HI, and DI

Abstract

Methyl iodide, hydrogen iodide, and deuterium iodide have been irradiated with x rays, whose energies are such that the most probable event is the formation of a vacancy in the L shell of iodine. The readjustment to this vacancy, principally by a series of Auger processes, gives rise to extensive ionization and decomposition; and the relative abundances of the fragment ions and their recoil‐energy spectra have been measured with a specially designed mass spectrometer. As the result of the inner‐shell vacancy, CH₃I decomposed primarily into hydrogen, carbon, and iodine ions, having, respectively, the average charges of 1+, 2+, and 5+. Very few molecular ions were observed. The recoil energies were quite large with values in some cases above 100 eV. A calculation, based on a simple model for a Coulombic ``explosion,'' is shown to be consistent with the data. In the studies made with HI and DI the recoil spectra of H⁺ and D⁺ are compared with calculations of the kinetic energies expected from multiple ionization. From this comparison there appears to be evidence that the multiply charged molecular ions separate slightly during the time the Auger processes are taking place. Finally, a brief discussion is given concerning the importance of the initial consequence of x‐ray interaction in radiation damage.