Mobilities and reactivities of molecular ions in combustion and hypersonics

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Conference Proceeding

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Mobility and reactivity are studied for the tertiary butyl cation (t-C 4H 9+), a major and stable product of fuel alkanes in ion-enhanced hydrocarbon combustion. The reduced zero-field mobilities of t-C 4H 9+ in He, N 2, O 2, and H 2O are determined to be K 0O (0) = 14.8 ± 0.6, 3.7 ± 0.8, 3.3 ± 0.8, and 0.04 ± 0.02 cm 2 V -1 s -1, respectively. While the mobility values in the nonpolar gases are in general agreement with theoretical calculations, the mobility in H 2O is extraordinary low. Collision-induced dissociation of t-C 4H 9+ indicates that the ion is stable with the dissociation threshold energy (E cm) of approximately 2 eV. Compared to other hydrocarbon cations, the t-C 4H 9++ ion is totally non-reactive with O 2, N 2O, NO, and NO 2 (k < 10 -12 cm 3 s -1) in a drift field of up to E/N ≈ 60 Td (E cm ≈ 0.7 eV). The study has also been extended to gas phase chemistry of deprotonated nitroalkane anions (R 2C=NO 2-), key intermediates in ion-enhanced combustion/detonation of nitroalkanes.

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AIAA Paper

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