We investigate theoretically the influence of magnetically tunable Fes
hbach collision resonances on the photoassociation spectra of ultracol
d atoms. As an example we consider recently predicted resonances for R
b-85 atoms. For excitation to the Rb-85(2) O-g(-)(S-1/2+P-1/2) electro
nic state, we predict that the photoassociation rate is resonantly enh
anced by at least two orders of magnitude. We find that photoassociati
on could serve as a useful probe with which to study Feshbach resonanc
es in ultracold collisions. In turn, these resonances should be very i
mportant to Pose-condensed gases, and more generally, to coherent atom
optics.