Determination of K-39 scattering lengths using photoassociation spectroscopy of the 0(g)(-) state

Threshold scattering properties of K-39 atoms are extracted from a line-sha pe analysis of photoassociation data. Specifically, we consider the rovibra tional levels (upsilon'=0-6) populated in the photoassociation process K(4S ) + K(4S)+ h p omega-->K-2*[0(g)(-)(upsilon',J')]. The measured spectra exh ibit several general trends, including large J' = 2 linewidths, large relat ive J' =4 peak intensities, and odd rotational lines which are weak or miss ing. The even J' features signal the presence of a d-wave shape resonance i n the ground-state collisions. The combination of spectral features allows us to place the following limits on the ground-state singlet and triplet sc attering lengths, a(s) = 140(-9)(+6) a.u. and a(t)= - 17-0.045(C-6- (C) ove r bar(6))+/-25 a.u., (C) over bar(6)= 3800 a.u. [S1050-2947(99)03512-X].