CALCULATED AND MEASURED DOUBLE-IONIZATION ENERGIES TO TRIPLET ELECTRONIC STATES OF THE DOUBLY-CHARGED IONS OF METHYLAMINE, DIMETHYLAMINE AND TRIMETHYLAMINE

Double ionization of methylamine, dimethylamine and trimethylamine was studied experimentally by double-charge-transfer spectroscopy and the oretically both using an ab initio method with different basis sets an d by the application of a semi-empirical form of the multiple scatteri ng X alpha (MSX alpha) method. The use of OH+ and F+ projectile ions i n the experimental work ensured that dications in triplet electronic s tates were produced. Also, the high velocity of the projectile ions en sured that vertical transitions from the molecules to the dications to ok place. Ab initio calculations predict quite well the observed reduc tion in the lowest double-ionization energies as the methyl content of the amine molecule increases. Application of the MSX alpha method all owed double-ionization energies to higher-lying tripler states of the dications to be predicted, providing a valuable insight into the elect ronic transitions which give rise to the spectra recorded for the thre e amines.