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Ion/molecule reactions in silane—carbon monoxide mixtures: possible synthesis of the SiC radical in the electric discharge chemistry

1990; Elsevier BV; Volume: 101; Issue: 2-3 Linguagem: Inglês

10.1016/0168-1176(90)87014-8

1873-2801

K. P. Lim, F. W. Lampe,

Advanced Chemical Physics Studies

The initial ion/molecule reactions characteristic of electric discharges in SiH4CO mixtures, namely the reactions of C+, CO+, SiH+2, SiH+ and Si+ with CO and SiH4 have been studied in a tandem mass spectrometer over a kinetic energy range of 1–7 eV (lab) and a pressure range of 1–10 mTorr. As is typical of systems involving positive ions and SiH4, the predominant reactions observed are hydride abstraction from SiH4 by C+ and CO+, both of which are highly exothermic and which occur with cross-sections of 26 and 87 Å2, respectively at 2eV laboratory energy. Other dominant reactions that form C bonds (and perhaps SiO bonds), and which we think may play a very important role in the recently reported synthesis of the SiC radical in COSiH4 discharges and in interstellar space, are reactions of C+ and CO+ with SiH4 that form CSiH+, the latter subsequently reacting by proton transfer with CO and perhaps with SiH4 to form the CSi radical. The CSiH+ ion also reacts with ND3 and H2 to form ND3H+ and H+3, which implies that in interstellar space CSi may be formed by reactions of CSiH+ with any molecule present having a proton affinity greater than 424 kJ mol−1.