NeMu* chemiluminescence: Radiolysis effects in gases

Near-infrared chemiluminescent emission from NeMu^*, the analogue of the Rydberg molecule NeH, has been observed in Ne, Ar, and Ne/Ar gas mixtures. Three temporally distinct features were observed: First, a large sharp emission peak at time zero, observed in all gases (Ne, He, N₂, Ar), is assigned to scintillation light during muon thermalization, probably caused by spur electrons. Second, a lowintensity broad region observed in all gases is attributed to e⁺ from muon decay. Finally, NeMu in 1–6 atm Ne with 0.1–2 torr Ar appeared as a high intensitydelayed emission, whose width and intensity depended linearly on the Ar concentration. Its wavelength spectrum from 680–960 nm was measured. Although questions remain as to how NeMu^* is formed, the precursor is likely Ne ⁺. Possible electron donors include metastable Ar^* (³ P ₂ or³ P ₀) and long-lived free (spur) electrons.Contribution from CEMAID, Center of Excellence in Molecular and Interfacial Dynamics; the financial support afforded by participation in Canada's National Centers of Excellence program is greatly appreciated.