G.D. Dickenson, E.J. Salumbides, M. Niu, Ch. Jungen, S.C. Ross, W. Ubachs
Recently a high precision spectroscopic investigation of the EF1Σg+-X1Σg+ system of molecular hydrogen was reported yielding information on QED and relativistic effects in a sequence of rotational quantum states in the X1Σg+ ground state of the H 2 molecule. The present paper presents a more detailed description of the methods and results. Furthermore, the paper serves as a stepping stone towards a continuation of the previous study by extending the known level structure of the EF1Σg+ state to highly excited rovibrational levels through Doppler-free two-photon spectroscopy. Based on combination differences between vibrational levels in the ground state, and between three rotational branches (O, Q, and S branches) assignments of excited EF1Σg+ levels, involving high vibrational and rotational quantum numbers, can be unambiguously made. For the higher EF1Σg+ levels, where no combination differences are available, calculations were performed using the multichannel quantum defect method, for a broad class of vibrational and rotational levels up to J=19. These predictions were used for assigning high-J EF levels and are found to be accurate within 5 cm -1. © 2012 American Physical Society.
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; Laboratoire Aimé Cotton du CNRS, Université de Paris-Sud, 91405 Orsay, France; Department of Physics and Centre for Laser, Atomic and Molecular Sciences, University of New Brunswick, Fredericton, NB E3B 5A3, P.O. Box 4400, Canada; Infrared Free Electron Laser Research Center, Tokyo University of Science, Noda, Chiba 278-8510, 2641 Yamazaki, Japan
