MASS-SPECTROMETRIC STUDY OF BIOMOLECULAR FORMATION OF DIATOMIC HELIUM ION

The homonuclear diatomic ion of He has been studied by a pulsed mass-spectrometric technique. These investigations of the bimolecular formation of He2+ show that at least four families of excited states take part in the process. Three of these states have excitation functions with peaks at 36, 58, and 68 eV, while the fourth peaks between 30-34 eV. Kinetic studies performed at these electron energies yielded the effective lifetimes, as well as specific reaction rates for the corresponding families of the excited states. The observed rate constants (1.8-3.6×10-9 cm 3 molecule-1·sec-1) correspond to reaction diameters comparable to collision diameters expected on the basis of simple theoretical consideration of the radius of the excited helium atom.