ELECTRON DECAY FOLLOWING d-c. DISCHARGE IONIZATION IN NO AND NO–Ne MIXTURES

Abstract

The time dependence of the electron density, Ne(t), and radiation temperature, Te(t), has been measured in d-c. discharge afterglows of NO and NO–Ne mixtures. Microwave wave-guide transmission and noise-sampling techniques were used. In pure NO the experimental results were compared with those computed for a recombination–attachment controlled plasma using Gunton and Shaw's values, and good agreement was found. In the NO–Ne mixtures p(Ne) was about 20 Torr, and p(NO) was varied from 0.5 × 10−3 to 0.10 Torr. It was found that 1/Ne(t) was linear over extensive ranges of Ne(t) indicating two-body electron–ion recombination. The results yield [Formula: see text] and the three-body attachment coefficient K = 2.2 × 10−31 cm6sec−1 for Te = Tgas = 300 °K. Te(t) decayed nonexponentially varying with p(NO) indicating that Penning ionization takes place together with other collision processes which are briefly discussed.

Survey of the gas-phase negative ion kinetics of inorganic molecules. Electron attachment reactions

“…More recently64 it has been demonstrated that these results are invalid since in actuality a sequence of reactions occur simultaneously, i.e., eq 60, which are rapid and have the effect of detaching electrons and thus reducing the apparent overall attachment rate. e + N2D -* O-+ N2 O" + N20 -* NO-+ NO (60) NO-+ M -* NO + e + M Chaney and Christophorou,91 using complementary drift tube and electron beam techniques, reexamined the variation of cross section vs. electron energy for process 59 and found that the cross section below 1.5 eV was quite sensitive to gas temperature. This result was quantified in a definitive electron beam study performed by Chantry139 in which the gas temperature was varied between 160 and 1040°K.…”

The dissociative recombination of NO+: the influence of the vibrational excitation state

“…NO + is also an abundant ion in lean flames and, again, its primary removal mechanism is dissociative recombination. It is not surprising, therefore, that there have been many studies of the rate of NO + recombination using a variety of techniques including stationary afterglows [2][3][4][5][6][7], shock tubes [8][9][10], flame sampling [11], ion trap [12], merged beams [13,14] and flowing afterglows [15][16][17]. Branching ratios for the products of the recombination have been measured using a photoionization method [18] and in a merged beams experiment [14].…”