Two-step excitation of Rb atoms on He nanodropletsM. Theisen, F. Lackner, F. Ancilotto, C. Callegari and W. E. ErnstEur. Phys. J. D, 61 2 (2011) 403-408DOI: https://doi.org/10.1140/epjd/e2010-10504-5