Spectroscopy study and modelling of an afterglow created by a low-pressure pulsed discharge in N-2-CH4

• Type: Article in International Scientific Journal
• Date: 2001

Authors

Carlos Daniel Diogo Matias Pintassilgo (Author) FEUP; Cernogora, G (Author) Other; Loureiro, J (Author) Other

Journal

Title: PLASMA SOURCES SCIENCE & TECHNOLOGY

Vol. 10

Pages: 147-161

Publisher: IOP Publishing

Indexing

ISI Web of Knowledge - 27 Citations

Scopus - 31 Citations

Other information

Authenticus ID: P-000-VRF

DOI: 10.1088/0963-0252/10/2/304

Abstract (EN): Time-resolved emission spectroscopy is used to investigate the relaxation of N-2(B-3 Pi (g)), N-2(C (3)Pi (u)) and CN(B(2)Sigma) states in the time afterglow of a low-pressure N-2-CH4 pulsed discharge, with time duration of 1 ms and in the range [CH4]/[N-2] = 0-2%. The decays in the relative measured concentrations in the afterglow are interpreted by modelling the relaxation of a set of time-varying kinetic master equations for the various species produced in the discharge, with conditions at the beginning of the afterglow calculated from a time-dependent kinetic model for the pulsed discharge. It is observed that the N-2(B (3)Pi (g)) State is populated in the afterglow mainly via the reaction N-2(A(3) Sigma (+)(u)) + N-2(X(1)Sigma (+)(g), 5 less than or equal to v less than or equal to 14) --> N-2(B(3)Pi (g)) +N-2(X(1)Sigma (+)(g) = 0), since the pulse duration is large enough to populate N-2(X(1)Sigma (+)(g), v) levels at its end and, to a smaller extent, also by pooling of N-2(A (3) Sigma (+)(u)). The N-2(C(3)Pi (u)) state is populated by pooling of N-2(A (3) Sigma (+)(u)) only, where as the CN(B (2)Sigma) State is created through reactions involving either on is large enough to populate the N-2(A (3) Sigma (+)(u)) states or N-2(X-1 Sigma (+)(g), v) levels in collisions with CN(X(2)Sigma (+)) molecules. The agreement between measured and calculated concentrations of N-2(B (3) Pi (g)) and N-2(C (3) Pi (u)) states is very good in pure N-2 and it may be considered satisfactory in the case of N2-CH4 mixtures, and for the CN(B (2)Sigma) State the agreement between theory and experiment is also reasonably good.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 15