Molecular beam experiments clarifying conflicting reports on magnetic field effects in NO(B) afterglows

A search for NO(BX) β-band emission from the impact of metastable Ar on N2O and metastable N2 on NO was conducted under single-collision conditions. For the cross sections to produce NO(B), upper limits of 0.001 and 0.1 Å2 respectively, were established. The β-band emission reported from afterglow studies of these two reactions was therefore probably due to a secondary process. Most likely NO(B 2Π) was formed via NO(a 4Π) as a precursor. This would explain the reported magnetic-field induced quenching of the β-band intensity, by the mechanism studied by us in a beam of NO(a 4Π). On the other hand, we detected β-band emission from the interaction of a beam containing metastable N atoms (as well as molecules) with N2O. This agrees with corresponding afterglow studies, where no magnetic field effect on this emission was observed. NO(B) being the primary product in this case, magnetic quenching would not be expected.