ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
The vibrational excitation and decay of N2(B 3Πg) state has been investigated in a N2 pulsed rf discharge. The effect of the pulsing frequency and the duty cycle on the N2 (B,v=1–12) vibrational distribution, obtained from the 1PG spectra taken at different times in discharge and afterglow, has been examined in the N2 pressure range 2.4 mTorr–1.5 Torr. The measured (B,v) distributions have been analyzed by a steady-state kinetic model taking into account the main excitation processes, like the electron impact from N2(X 1Σg+,v) and N2(A 3Σu+,v) states, the associative excitation of N2(X,v) with N2(A,v), the pooling by N2(A,v) molecules, the atomic recombination of N(4S), as well as the quenching processes. For the various processes, experimental state-to-state rate coefficients from the literature and/or calculated data sets have been used. Measured N2(A,v) and electron energy distribution functions, and estimated N2(X,v) distributions have been used as input data for the model. The model satisfactorily reproduces almost all the measured distributions. The kinetic analysis evidences that the shape of the (B,v=1–12) distribution depends on the competition between the different processes and in turn on the time variation of both density and the degree of internal excitation of the reaction species with discharge repetition rate, duty cycle, and pressure. In general, in the discharge the electron impact is always the predominant excitation mechanism, while the processes involving long-lived species: N2(A,v) and N2(X,v) are important in the postdischarge regime. Under conditions of high metastable density, the associative collision processes contribute to (B,v) excitation in the discharge, and the electron impact process from the A and X states gives a non-negligible contribution to the low v levels in the millisecond time scale afterglow. An analysis of the B quenching is carried out. © 1999 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.477938
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