DOUBLE-IONIZATION OF THE N-ALKYL IODIDES C2H5I, C3H7I AND C4H9I

Double ionization of C2H5I, n-C3H7I and n-C4H9I has been investigated experimentally using double-charge-transfer spectroscopy. On the assum ption that spin is conserved in the double-electron-capture reactions, and because of the use of OH+ as the projectile ion, it is probable t hat triplet states of the dications were populated. Peaks in the spect ra were interpreted in terms of the electronic transitions giving rise to double-ionization energies calculated using a semi-empirical versi on of the multiple scattering X alpha (MSX alpha) method of molecular orbital calculations. The density of states was found to increase as t he alkyl chain-length increased, and most of the peaks observed were i nterpreted as being due to transitions to groups of close-lying states . In addition to the use of the MSX alpha method, ab initio double-ion ization energies to the lowest triplet states of the dications were ca lculated.