We present preliminary results on Submillimeter Array (SMA) observations of three Luminous Infrared Galaxies (LIRGs) and one infrared Quasi Stellar Object (IR QSO). The galaxies were observed at sub-kpc spatial resolution in lines of CO and 13CO, as well as in the continuum at 1.3mm. The moment maps show that the molecular gas in these galaxies is distributed in rotating disks with velocity gradients ranging from ~30 to 120 km s−1 kpc−1. Combined with archival CO J=3-2 data, the spatial distributions of the CO J=3-2/J=2-1 ratios shows clear variations across the galaxies. The brightness temperature of the overlap region in VV 114 is found to be lower than that in the nuclear region of VV 114E, suggesting that that the bulk of molecular gas in this region is sub-thermalized.