Observation of an Optical Feshbach Resonance in $^{88}$Sr

We have observed an optical Feshbach resonance (OFR) using the narrow intercombination line in $^{88}$Sr. As suggested by Ciurylo et. al [Phys. Rev. A 71, 030701(R) (2005)], the scattering wave function is changed by applying an additional laser to the trapped atom sample and varying its intensity and detuning from a molecular level near the intercombination line transition. We use the change in the rate of thermalization of atoms as our diagnostic and a model of evaporation to determine the corresponding scattering length. While the change in scattering length due to the OFR is accompanied by modest losses, the decreased sample temperature leads to a slight increase in the phase space density of the sample. Demonstration of the OFR without large atom loss offers fine control of the properties of the atomic system.