Precision spectroscopy of high rotational states in H2 investigated by Doppler-free two-photon laser spectroscopy in the EF 1u0002+g system

摘要

Recently a high precision spectroscopic investigation of the EF 1u0002n+ng –X 1u0002n+ng system of molecular hydrogennwas reported yielding information on QED and relativistic effects in a sequence of rotational quantum statesnin the X 1u0002n+ng ground state of the H2 molecule [Salumbides et al., Phys. Rev. Lett. 107, 043005 (2011)]. Thenpresent paper presents a more detailed description of the methods and results. Furthermore, the paper serves as anstepping stone towards a continuation of the previous study by extending the known level structure of the EF 1u0002n+ngnstate to highly excited rovibrational levels through Doppler-free two-photon spectroscopy. Based on combinationndifferences between vibrational levels in the ground state, and between three rotational branches (O, Q, and Snbranches) assignments of excited EF 1u0002n+ng levels, involving high vibrational and rotational quantum numbers,ncan be unambiguously made. For the higher EF 1u0002n+ng levels, where no combination differences are available,ncalculations were performed using the multichannel quantum defect method, for a broad class of vibrational andnrotational levels up to J = 19. These predictions were used for assigning high-J EF levels and are found to benaccurate within 5 cm−1.