The Radio-Frequency Spectrum of H₂⁺

For the 2~ ground electronic state of 112+ the first-order rho-type doubling constant d' is calculated for the first nine vibrational energy levels. The values of d' for the vibrational levels with v = 6 and v = 7 agree to better than 0.4 MHz with the experimental measurements of Jefferts. This result and some rough theoretical estimates indicate that the second-order contribution d" is very small. With a value of d that takes into account the vibrational effects, a recalculation of the hyperñne structure of ortho-Hi~ (N =1) has yielded radio frequencies which are probably reliable to better than 1 MHz