Ultraprecise determination of the 2p radiative lifetime of lithium

Summary form only given. An indirect method for experimentally determining atomic lifetimes can be realized through the analysis of long-range vibrational levels of singly excited diatomic molecules. For the case of an alkali-metal homonuclear diatomic molecule, this long-range interaction potential is dominated by a resonant dipole-dipole interaction that has the functional form, V(R)=-C/sub 3//R/sup 3/, where R is the internuclear separation of the two atoms. The C/sub 3/ coefficient can be related directly to the dipole matrix element connecting the ground s and excited p atomic states, and is therefore inversely related to the p-state radiative lifetime. Photoassociative spectroscopy of ultracold /sup 6/Li and /sup 7/Li has enabled us to accurately determine the high-lying vibrational levels of the singly excited A/sup 1//spl Sigma//sub u//sup +/ state of /sup 6/Li/sub 2/ and /sup 7/Li/sub 2/, which can be used to extract C/sub 3/ and determine the lithium 2p atomic lifetime.