Electron and ion reactions with hexamethyldisiloxane and pentamethyidisiloxane

摘要

The dissociative recombination of electrons with the hexamethyldisiloxane (HMDSO) cation, ((CH3)3Si-O-Si(CH3)3)~+ and the pentamethyldisiloxane cation ((CH3)3Si-O-Si(CH2)2)~+ as well as the ion-molecule reaction between Ar~+ and HMDSO have been studied at 300 K using a flowing afterglow Langmuir probe-mass spectrometer apparatus. The rate constants for these reactions, measured directly for the first time, are, respectively, alpha_1 = 1.8X10~(-6), alpha_2=3.6X10~(-6) cm~3/s, and k =2.0X10~(-9) cm~3/s with uncertainties of ±30%. In addition, the electronic attachment to neutral HMDSO was also studied and an upper limit value of the rate constant was determined to be beta =3.3X10~(-11) cm~3/s.