Rovibrational levels (v=0--30) of the ${0}_{\mathrm{g}}^{\mathrm{\ensuremath{-}}}$ ``pure long-range'' state of $^{39}\mathrm{K}_{2}$ are observed by photoassociative spectroscopy of ultracold potassium atoms prepared in a high-density magneto-optical trap. The measured molecular binding energies are used to precisely determine the long-range dipole-dipole potential constant ${\mathrm{C}}_{3}^{\mathrm{\ensuremath{\Pi}}}$ of the K(4s)+K(4p) asymptote and the radiative lifetime of the 4p state. We determine ${\mathrm{C}}_{3}^{\mathrm{\ensuremath{\Pi}}}$=-5.456(9) zJ ${\mathrm{nm}}^{3}$ (-8.445(14) a.u.), \ensuremath{\tau}(4 ${\mathrm{}}^{2}$ ${\mathrm{P}}_{3\mathrm{/}2}$ )=26.34(5) ns, and \ensuremath{\tau}(4 ${\mathrm{}}^{2}$ ${\mathrm{P}}_{1\mathrm{/}2}$ )=26.69(5) ns. Our result is a significant improvement in precision over previous lifetime measurements and agrees well with the recent fast-beam experiment [U. Volz and H. Schmoranzer, Phys. Scr. T65, 48 (1996)].Rovibrational levels (v=0--30) of the ${0}_{\mathrm{g}}^{\mathrm{\ensuremath{-}}}$ ``pure long-range'' state of $^{39}\mathrm{K}_{2}$ are observed by photoassociative spectroscopy of ultracold potassium atoms prepared in a high-density magneto-optical trap. The measured molecular binding energies are used to precisely determine the long-range dipole-dipole potential constant ${\mathrm{C}}_{3}^{\mathrm{\ensuremath{\Pi}}}$ of the K(4s)+K(4p) asymptote and the radiative lifetime of the 4p state. We determine ${\mathrm{C}}_{3}^{\mathrm{\ensuremath{\Pi}}}$=-5.456(9) zJ ${\mathrm{nm}}^{3}$ (-8.445(14) a.u.), \ensuremath{\tau}(4${\mathrm{}}^{2}$${\mathrm{P}}_{3\mathrm{/}2}$)=26.34(5) ns, and \ensuremath{\tau}(4${\mathrm{}}^{2}$${\mathrm{P}}_{1\mathrm{/}2}$)=26.69(5) ns. Our result is a significant improvement in precision over previous lifetime measurements and agrees well with the recent fast-beam experiment [U. Volz and H. Schmoranzer, Phys. Scr. T65, 48 (1996)].

Physical Review AMar 1, 199793 citations

Rovibrational levels (v=0--30) of the ${0}_{\mathrm{g}}^{\mathrm{\ensuremath{-}}}$ ``pure long-range'' state of

^{39}\mathrm{K}_{2}

are observed by photoassociative spectroscopy of ultracold potassium atoms prepared in a high-density magneto-optical trap. The measured molecular binding energies are used to precisely determine the long-range dipole-dipole potential constant ${\mathrm{C}}_{3}^{\mathrm{\ensuremath{\Pi}}}$ of the K(4s)+K(4p) asymptote and the radiative lifetime of the 4p state. We determine ${\mathrm{C}}_{3}^{\mathrm{\ensuremath{\Pi}}}$=-5.456(9) zJ

{\mathrm{nm}}^{3}

(-8.445(14) a.u.), \ensuremath{\tau}(4

{\mathrm{}}^{2}

{\mathrm{P}}_{3\mathrm{/}2}

)=26.34(5) ns, and \ensuremath{\tau}(4

{\mathrm{}}^{2}

{\mathrm{P}}_{1\mathrm{/}2}

)=26.69(5) ns. Our result is a significant improvement in precision over previous lifetime measurements and agrees well with the recent fast-beam experiment [U. Volz and H. Schmoranzer, Phys. Scr. T65, 48 (1996)].