Near-infrared Luminescence Spectra Research Articles

Luminescence spectra of solid nitrogen excited by electron impact

The visible and near-infrared luminescence spectrum of pure solid nitrogen has been reinvestigated. Spectral intensity distributions, decay curves, and the temperature dependence of these characteristics have been measured in a variable-temperature liquid-helium cryostat, using pulsed electron-beam excitation and a photoelectrically recording spectrometer. The parity-forbidden transitions within the ground configuration of trapped atomic nitrogen, 2P→2D and 2D→4S, are observed as dipole radiation which is induced by the dynamical perturbing fields of inter- and intramolecular vibrations. The presence of slowly relaxing, vibrationally excited N2 molecules, 3⩽v⩽13, is confirmed. The vibrational excitation of N2 and electronic excitation of N is ascribed to a common process, namely to the quenching of molecular triplet excitons, N2 A 3Σ, v′≃0, by ground-state atoms, N 4S. This process yields N (2P or 2D) and N2 X 1Σ, v″, at adjacent lattice sites, with initial distributions of v″ populations that show half-widths spanning approximately four quanta, and maxima near v″≃9.