@article {200,
	title = {Negative-continuum effects on the two-photon decay rates of hydrogenlike ions},
	journal = {Physical Review A (Atomic, Molecular, and Optical Physics)},
	volume = {80},
	number = {5},
	year = {2009},
	pages = {052511},
	abstract = {Two-photon decay of hydrogenlike ions is studied within the framework of second-order perturbation theory, based on the relativistic Dirac{\textquoteright}s equation. Special attention is paid to the effects arising from the summation over the negative-energy (intermediate virtual) states that occur in such a framework. In order to investigate the role of these states, detailed calculations have been carried out for the 2s1/2{\textendash}>1s1/2 and 2p1/2{\textendash}>1s1/2 transitions in neutral hydrogen H as well as for hydrogenlike xenon Xe53+ and uranium U91+ ions. We found that for a correct evaluation of the total and energy-differential decay rates, summation over the negative-energy part of Dirac{\textquoteright}s spectrum should be properly taken into account both for high-Z and low-Z atomic systems.},
	keywords = {atomic structure Dirac equation hydrogen neutral atoms perturbation theory relativistic corrections spontaneous emission uranium xenon},
	doi = {DOI: 10.1103/PhysRevA.80.052511},
	url = {http://link.aps.org/abstract/PRA/v80/e052511},
	author = {A. Surzhykov and J P Santos and P Amaro and P. Indelicato}
}
