Abstract
We consider the excitation dynamics of the two-photon - transition in a beam of atomic hydrogen by laser radiation. Specifically, we study the impact of ionization damping on the transition line shape, caused by the possibility of ionization of the level by the same laser field. Using a Monte Carlo simulation, we calculate the line shape of the - transition for the experimental geometry used in the two latest absolute frequency measurements [M. Niering et al., Phys. Rev. Lett. 84, 5496 (2000) and M. Fischer et al., Phys. Rev. Lett. 92, 230802 (2004)]. The calculated line shift and linewidth are in excellent agreement with the experimentally observed values. From this comparison we can verify the values of the dynamic Stark shift coefficient for the - transition for the first time on a level of 15%. We show that the ionization modifies the velocity distribution of the metastable atoms, the line shape of the - transition, and has an influence on the derivation of its absolute frequency.
- Received 19 June 2006
DOI:https://doi.org/10.1103/PhysRevA.74.052504
©2006 American Physical Society