Collision relaxation cross section of highly vibrationally excited molecules

Through quantum-beat spectroscopy collision relaxation of a high vibrational level of SO2 43877.52 cm(-1) is characterized. highly excited vibrational level. The deduced relaxation cross section of this excited level by A is 216 Angstrom(2), 5 times the area of the hard sphere, and by an ambient temperature SO2 molecule is 969 Angstrom(2), almost 20 times the hard sphere. These cross sections indicate that relaxation collisions of highly vibrationally excited molecules have effective distances much longer than van der Waals radii and involve mechanisms qualitatively different from lower excitations.