1. Bender, P.L., Hall, J.L., Garstang, R.H., Pichanick, F.M.J., Smith, W.W., Barger, R.L., West, J.B.: Bull. Am. Phys. Soc. Ser. II21, 599 (1976)
2. Ertmer, W., Blatt, R., Hall, J.L.: J. Quant. Electron.8, 249 (1984)
3. Hall, J.L., Zhu, M., Buch, P.: J. Opt. Soc. Am. B6, 2194 (1989)
4. Dirscherl, J., Walther, H.: Abstract 1H3, 14th International Conference on Atomic Physics, Boulder, 1994
5. Dirscherl, J.: Personal communication. The estimate (0.2 s) for the lifetime of the Ag I 4d 9 5s 2 2 D 5/2 metastable level is based on an extrapolation of the measured lifetime (0.09 s [6]) of the corresponding 5d 9 6s 2 2 D 5/2 metastable level in Hg+ by considering the ?5-dependence of theE2 decay (see also [1])