M.L. Niu, E.J. Salumbides, G.D. Dickenson, K.S.E. Eikema, W. Ubachs
Accurate experimental values for the vibrational ground tone or fundamental vibrational energy splitting of H2, HD, and D2 are presented. Absolute accuracies of 2×10-4 cm-1 are obtained from Doppler-free laser spectroscopy applied in a collisionless environment. The vibrational splitting frequencies are derived from the combination difference between separate electronic excitations from the X 1Σg+,v=0,J and v=1,J vibrational states to a common EF1Σg+,v=0,J state. The present work on rotational quantum states J=1,2 extends the results reported by Dickenson et al. on J=0 [Phys. Rev. Lett. 110 (2013) 193601]. The experimental procedures leading to this high accuracy are discussed in detail. A comparison is made with full ab initio calculations encompassing Born-Oppenheimer energies, adiabatic and non-adiabatic corrections, as well as relativistic corrections and QED-contributions. The present agreement between the experimental results and the calculations provides a stringent test on the application of quantum electrodynamics in molecules. Furthermore, the combined experimental-theoretical uncertainty can be interpreted to provide bounds to new interactions beyond the Standard Model of Physics or fifth forces between hadrons. © 2014 Elsevier Inc. All rights reserved.
Department of Physics and Astronomy, LaserLaB, VU University, 1081HV Amsterdam, de Boelelaan 1081, Netherlands; Department of Physics, University of San Carlos, Cebu City 6000, Philippines
