Metastable level lifetimes from electron-shelving measurements with ion clouds and single ionsM. Knoop, C. Champenois, G. Hagel, M. Houssin, C. Lisowski, M. Vedel and F. VedelEur. Phys. J. D, 29 2 (2004) 163-171DOI: https://doi.org/10.1140/epjd/e2004-00022-6