He/sub 2/(d /sup 3/. sigma. /sub u//sup +/) decay rate in a high-pressure helium afterglow

We report a total collisional quenching rate of (8.2 +- 0.6) x 10/sup 4/ Torr/sup -1/ sec/sup -1/ at 293 /sup 0/K for He/sub 2/(d /sup 3/..sigma../sub u/) molecules colliding with ground state He atoms. This rate is determined by observing the decay rate of dye-laser induced d /sup 3/..sigma../sub u//sup +/..-->..b /sup 3/Pi/sub g/ fluorescence over a pressure range of 50 to 700 Torr.