AbstractCollision relaxation cross sections of asingle, highly vibrationally excited level in the ground electronic state of SO2at 44877.52 cm−1above the zero‐point by the collision partner CO has been measured in a supersonic expansion using the kinetic quantum beat spectroscopic technique. The depopulation cross section at 14.5 K for this SO2*‐CO system has been determined to be 75 Å2, while the dephasing cross section is 22 Å2. Comparison with previously measured cross sections for the SO2*‐SO2, SO2*‐inert gases systems at room temperature using a similar spectroscopic approach reveals both the long range interaction and repulsive force contributions to the relaxation cross sections of highly vibrationally excite