Searching for the N2 <i>A</i>′ 5Σ state

The memory effect, the phenomenon that some active species survive very long afterglow periods and affect subsequent breakdown, was observed more than 40 years ago. The effects have been observed even over periods of several hours. Attempts to explain the memory effect in nitrogen were mostly based on hypothetical metastables and on the A3Σ state. However, such explanations had to neglect some quenching processes which are known to be very effective under the conditions of the experiments. The explanation based on atoms remaining from the previous discharge and recombining on the cathode to produce initial electrons was shown to be fully consistent with all the experimental data for nitrogen including a wide range of pressures and the addition of oxygen impurities. The memory effect was also shown to be sensitive to the work function of the cathode material. Thus, an attempt was made to use the memory effect as a diagnostic tool to establish the data on the dominant loss of nitrogen atoms from the discharge which is recombination on the walls of the tube. However, a possible role of higher vibrational levels has not been fully addressed, mainly due to the shortage of data. On the other hand, the memory effect which was observed for rare gases cannot be explained on the basis of the standard data unless the presence of molecular impurities is invoked. Another open issue would be the role of charges accumulated on the glass surfaces and whether those may be released to the gas phase. The aim of this paper is to summarize the achievements of the model based on atom recombination and to point out how the breakdown model associated with the memory effect may be completed and how it may be applied in practical discharges.

show abstract

“…. ) are short-lived (Lofthus andKrupenie 1977, Young andBower 1990), so these processes are instantaneous on the timescale studied here.…”

Section: Electron Yield From the Gas Phase Metastable Statesmentioning

confidence: 89%

Memory effects in the afterglow: open questions on long-lived species and the role of surface processes

Petrović¹,

Marković²,

Pejović³

et al. 2001

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…It is not yet known, e.g., to what extent the precursor formed is N 2 ðA 3 R þ u Þ or N 2 ðA 05 R þ g Þ, that in turn forms N 2 (B 3 P g ) by collisional energy transfer, despite the progress made in studies of excitation into the N 2 (B 3 P g ) state by collisional intersystem energy transfer from the N 2 ðA 3 R þ u Þ and N 2 ðA 05 R þ g Þ states. These studies show insignificant direct collisional coupling between the N 2 ðA 05 R þ g Þ and the N 2 (B 3 R g ) states apart from the gateway mechanisms discovered for m = 10, 11 and 12 of the isotopic 14 N 2 (B 3 P g,m ) state only [3][4][5][6][33][34][35][36][37]…”

Section: The Role Of Oxygenmentioning

confidence: 99%