COLLISIONAL ENERGY-TRANSFER IN THE 2-CHANNEL THERMAL UNIMOLECULAR REACTION OF CHLOROETHANE-1,1,2-D(3)

The two-channel unimolecular decomposition of chloroethane-1,1,2-d(3) was studied over the temperature range 663.2-763.2 K. Arrhenius parame ters for this reaction were found to be log(A(H)/s(-1)) = 12.89 +/- 0. 04, E(aH) = 225.82 +/- 4.97 kJ/mol (HCl elimination) and log(A(D)/s(-1 )) = 12.60 +/- 0.04, E(aD) = 230.46 +/- 5.17 kJ/mol (DCl elimination). The average collisional energy-transfer quantities, [Delta E](down) a nd [Delta E](all), were evaluated for the pure reactant itself and wit h various collider gases including CH4, CF4, CF3H, CF3Cl, and CF3Br. T he stepladder model for the transition probability-was used in this ev aluation. The values of [Delta E](down) for the C-1 collider molecules increase with their boiling point according to the linear relation [D elta E](down) (cm(-1)) = (7.56 +/- 0.51)T-b (K) - (285 +/- 0.63). The [Delta E](down) values were also found to increase with an attractive potential parameter defined in terms of a combination of polarizabilit ies and dipole moments of collider gases. On the other hand, it was fo und, within the temperature range stated, that [Delta E](down) has an inverse dependence on temperature given by the expressions [Delta E](d own) proportional to T--0.7 for CH2DCD2Cl and [Delta E](down) proporti onal to T--2.3 for CF4.