Cold rubidium molecule formation through photoassociation: A spectroscopic study fo the 0_g~- long-range state of ~(87)Rb_2

摘要

We report the detailed analysis of translationally cold rubidium molecule formation through photoassociation. Cold molecules are formed after spontaneous decay of photoexcited molecules from a laser cooled atomic sample, and are detected by selective mass spectroscopy after two-photon ionization into Rb_2~+ ions. A spectroscopic study of the 0_g~- (5S + 5P_(3/2)) pure long-range state of ~(87)Rb_2 is performed by detecting the ion yield as a function of the photoassociation laser frequency; the spectral data are theoretically analyzed within the semiclassical RKR approach. Molecular ionization is resonantly enhanced through either the 2~3Π_g or the 2~3Σ_g~+ intermediate molecular states. Some vibrational levels of the latter electronic state are observed and assigned here for the first time. Finally, cold molecules formation rates are calculated and compared to the experimentally measured ones, and the vibrational distribution of the formed molecules in the α~3Σ_u~+ ground triplet state is discussed.