Precision Spectroscopy of Molecular Hydrogen Ions: Towards Frequency   Metrology of Particle Masses
  We describe the current status of high-precision ab initio calculations of the spectra of molecular hydrogen ions (H_2^+ and HD^+) and of two experiments for vibrational spectroscopy. The perspectives for a comparison between theory and experiment at a level of 1 ppb are considered. 
B. Roth, J. Koelemeij, S. Schiller, L. Hilico, J.-Ph. Karr, V.I.   Korobov, D. Bakalov