Evidence for the state mixing collision is given, where the principal quantum number n ranges' from 26 to 4. The laser induced Xe(nf) atoms transfer their excitation to one or more Xe(^nf) reservoirs during collisions with ammonia. Measurements of the collisional ionization in a 3.7 v/cm field reveal Xe+ ion signals at times which are long compared to the radiative lifetime of the laser induced state. From this data, the absolute collisional ionization rate constants for the Xe(j^nf) reservoirs are obtained. Simultaneous measurements of the number of Xe(nf) atoms excited by the laser allows one to derive absolute rate constants for the depopulation of Xe(nf) atoms due to state mixing and direct collisional ionization. A serial model for reservoir formation is used in conjunction with a computer data fitting routine to derive the above rate constants.