The production of Ominus;, NOminus;and N2Ominus;by electron impact on N2O has been studied as a function of pressure in the range 10minus;6to 5thinsp;times;thinsp;10minus;3torr, using a quadrupole mass filter. The respective linear, quadratic, and cubic pressure dependences observed for these ions and their relative signals are consistent with the following reaction sequence and cross sections:eplus;N2Othinsp;rarr;thinsp;Ominus;plus;N2,Ominus;plus;N2Othinsp;rarr;thinsp;NOminus;plus;NOlpar;3thinsp;times;thinsp;10minus;16cm2rpar;,NOminus;thinsp;plus;thinsp;N2Othinsp;rarr;thinsp;N2Ominus;thinsp;plus;thinsp;NOlpar;1thinsp;times;thinsp;10minus;16cm2rpar;.. An alternative explanation of the data in terms of the threehyphen;body reaction converting Ominus;to N2Ominus;is rejected due to the implausibly large coefficient required to explain the data. No other reactions were detected. Discrepancies between the present results and those of other workers are discussed quantitatively. It is suggested that N2Ominus;formation by the presently proposed reaction may well be endothermic, accounting for its nonappearance in systems used to study thermal energy reactions.
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