chemical physics of discharges - Argonne National Laboratory

chemical physics of discharges - Argonne National Laboratory chemical physics of discharges - Argonne National Laboratory

26.03.2013 Views

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where DISCUSSION OF XESULTS PERTAINING TO ATOMIC NITROGEN The observations indi,cate that duriyg decay 1 1 - = - T 0 + K [NI2 [MI with K 2 4 x cm9/sec. Neither or can be the radiative lifetime of N2(A3X3 'which is 210 sec. The differential equation describing the time dependence of 3+ d[N2(A Eu) 1 dt = ' P - L. [N2(A 3 Eu)] + I 3+ [N2(A Zu)] is 3+ where L contains all factors other than [N2(A XU)] such as collision partner concentrations, rates of radiation or diffusion, s., that are involved in processes removing N2(A3Et), and where P is the rate of production. Substituting Eq. (1) in Eq. (3) gives or Then either 3 + -t/.'o 1 [N2(A Eu) lo e (L--) = P . (4) 'a 1 L = - Ta P 1 3+ (L - [N2(A Xu) lo a (3) and P = O (5) -t/Ta , = e (6) -t/Ta In the latter eventuality L > l/ia, since neither P nor e can be negative. If L is comparable to 1/~~, it must be essentially constant in time,' while if it is large compared to l/ia, Since all constitutents of the system probably decay when the power input is stopped, would be characteristic of the decay of a reactant concentration ia involved in P to a higher power than in L, while other reactant concentrations are either constant or common to both P and L. The previous statement would be true if a product of reactant concentrations replaces a single reactant concentration. Since 1 / changes ~ ~ by almost a factor of 10 over the range of [N] used, either L >> 1/~, for small [N] and hence P/L [N2(A3E;)lo = e-t/Ta, or L

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