LINE-SHAPES OF HIGH-RESOLUTION PHOTOASSOCIATION SPECTRA OF OPTICALLY COOLED ATOMS

High resolution photoassociation spectra of colliding ultracold trappe d atoms contain detailed information about ground and excited state in teractions. We calculate the asymmetric line shapes for ultracold Na-2 absorption using a resonance scattering expression, proportional to a free-bound Franck-Condon factor, that is justified by full quantum sc attering calculations of a collision in a radiation field. The line sh apes illustrate Wigner threshold law behavior, which is characteristic of the quantum limit as T --> 0. Using an adiabatic hyperfine analysi s, we calculate and compare a model spectra for J = 1, 2, 3, and 4 fea tures of the Na-2 (IIg)-I-1(v = 48) state to recent high resolution ex perimental data.