The normal state of the helium molecule-ions He-2(+) and He-2(++)

Abstract

With the use of wave functions constructed from hydrogen-like single-electron functions with an effective nuclear charge Z, the application of the variation method of treating the wave equation for the normal state of He, involving a three-electron bond, leads to the values Z = 1.833, r0 = 1.085A, De = 2.47 v.e., and 0 = approximately 1950 cm(-1). The experimentally determined values (from the He2 spectrum) are r0 = 1.090A, De = 2.5 v.e., and ½ = 1628 cm(-1). A similar discussion of He, with a covalent-plus-ionic wave function, shows that the energy curve has a minimum at r0 = 0.75A, 0 = approximately 3200 cm(-1), with a maximum 1.4 v.e. higher at about 1.1A. This configuration could act as the core for excited states of He and doubly-excited states of He2, some of which would be capable of existence with either one of two moments of inertia, one corresponding to r0 = 0.75A and the other to about the same values of r0 as for the analogous states in excited H or doubly-excited H2.