On the 1S → 1D emission of O by exciting O2 into and beyond the Schumann-Runge continuum in Ar matrices at 15 K

Photolysis of O2 dispersed in solid neon with far-ultraviolet radiation

Irradiation at 173 or 143 nm of samples of ¹⁶O₂ or ¹⁸O₂ in solid Ne near 4 K produced many new spectral lines in absorption and emission from the mid-infrared to the near-ultraviolet regions. The major product was ozone, O₃, that was identified with its mid-infrared and near-ultraviolet absorption lines. Oxygen atoms were formed on photolysis of O₂ and stored in solid neon until the temperature of a sample was increased to 9 K, which enabled their migration and combination to form O₃ and likely also O₂. O₂ in five excited states and O in two excited states detected through the emission spectra indicate that complicated processes occurred in solid Ne after far-ultraviolet excitation. For the transition ¹D₂ → ³P_1,2 of O, the lifetime was determined to be 5.87 ± 0.10 s; the lifetime of the upper state of an unidentified transition associated with an emission feature at 701.7 nm was determined to be 2.34 ± 0.07 s.

Charging effects in an electron bombarded Ar matrix and the role of chemiluminescence-driven relaxation

The relaxation processes in pure and doped Ar films preirradiated by an electron beam are studied with the focus on charging effects. Correlated real time measurements have been performed applying current and optical activation spectroscopy methods. Thermally stimulated exoelectron emission and thermally stimulated luminescence are detected in the vacuum ultraviolet and visible range. An appreciable accumulation of electrons in the matrix is found, and prerequisites for negative space charge formation are ascertained. The part played by pre-existing and radiation-induced defects as well as dopants is considered and the temperature range of the electron trap stability is elucidated. It is shown that laser-induced electron detachment from O(-) centers results in an enhancement of electron detrapping via the chemiluminescence mechanism, viz. neutralized and thermally mobilized O atoms recombine. Formation of O(2)* results in the emission of visible photons. These photons act as a stimulating factor for electron release and transport, terminating in exoelectron emission and charge recombination. Chemiluminescence therefore plays an important role in the decay of charged centers.