We report observations of photoassociation (PA) spectra near the intercombination line in isotopic mixtures of ultracold ytterbium gases. Several heteronuclear bound states have been found for the excited (YbYb)-Yb-170-Yb-174 and (YbYb)-Yb-174-Yb-176 molecules. We develop a single-channel mass-scaled interaction model for the excited state molecule which well reproduces the measured bound state energies. This is an important step toward optical control of interactions in mixtures of ultracold ytterbium gases using heteronuclear optical Feshbach resonances. The model developed is applicable in collisions of other similar systems, such as cadmium and mercury.