Flowing afterglow system

F. C. Fehsenfeld, A. L. Schmeltekopf, D. M. Dunkin, and E. E. Ferguson, Compilation of Reaction Rate Constants Measured in the ESSA Flowing Afterglow System to August, 1969, ESSA Technical Report ERL 135-AL3 (September 1969), U.S. Gov t. Priniting Office. 

A. L. Farragher, Ion-molecule reaction rate studies in a flowing afterglow system, Trans. Faraday Soc. 66, 1411-1422 (1970). 

D.B. Dunkin, F.C. Fehsenfeld, A.L. Schmeltekopf, and E.E. Ferguson, Ion-molecule reaction studies from 300° to 600°K in a temperature-controlled flowing afterglow system, J. Chem. Phys. 49, 1365-1371 (1968). 

A schematic of a typical version of the NOAA flowing afterglow system is shown in Fig. 1. In brief, a large flow of buffer gas (180 atm cm sec" ), usually helium, is introduced into the front end of a stainless steel tube approximately 8 cm in diameter, down which it is exhausted by a large pump, typically at 10" cm sec" and with 0.3 Torr pressure. A suitable source gas to produce the desired reactant ions is added either with the helium or downstream of the helium addition as shown in Fig. 1. The helium (and the source ion gas if it is added ahead of the electron gun) are ionized by an electron beam of variable voltage and current in such a fashion as to produce the desired reactant ion in the flowing stream before arrival at the neutral reactant addition port. The ion composition is... 

It is also possible to vary the temperature from 80 to 600°K in the flowing afterglow system, which allows the energy dependence of the... 

Finally, it is possible in some cases to observe the emission spectrum of an ion-molecule reaction in the flowing afterglow system and acquire information as to the product states formed. An example will be discussed below. 

Fig. 9. Ion currents in the flowing afterglow system as a function of added NO flow, illustrating rapid reaction N02 + NO->...

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