Precision measurement of the rotational energy-level structure of the three-electron molecule He-2(+)

摘要

The term values of all rotational levels of the He-4(2)+ X+ S-2(u)+ (nu(+) = 0) ground vibronic state with rotational quantum number N+ <= 19 have been determined with an accuracy of 8 x 10(-4) cm(-1) (similar to 25 MHz) by multichannel-quantum-defect-theory-assisted Rydberg spectroscopy of metastable He-2*. Comparison of these term values with term values recently calculated ab initio by Tung et al. [J. Chem. Phys. 136, 104309 (2012)] reveals discrepancies that rapidly increase with increasing rotational quantum number and reach values of 0.07 cm(-1) (similar to 2.1 GHz) at N+ = 19. Published by AIP Publishing.